WordPress 源代码——主干（underscore-1.4.1.js）

//     Underscore.js 1.4.1
2  //     http://underscorejs.org
3  //     (c) 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.
4  //     Underscore may be freely distributed under the MIT license.
5  
6  (function() {
7  
8    // Baseline setup
9    // --------------
10  
11    // Establish the root object, `window` in the browser, or `global` on the server.
12    var root = this;
13  
14    // Save the previous value of the `_` variable.
15    var previousUnderscore = root._;
16  
17    // Establish the object that gets returned to break out of a loop iteration.
18    var breaker = {};
19  
20    // Save bytes in the minified (but not gzipped) version:
21    var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
22  
23    // Create quick reference variables for speed access to core prototypes.
24    var push             = ArrayProto.push,
25        slice            = ArrayProto.slice,
26        concat           = ArrayProto.concat,
27        unshift          = ArrayProto.unshift,
28        toString         = ObjProto.toString,
29        hasOwnProperty   = ObjProto.hasOwnProperty;
30  
31    // All **ECMAScript 5** native function implementations that we hope to use
32    // are declared here.
33    var
34      nativeForEach      = ArrayProto.forEach,
35      nativeMap          = ArrayProto.map,
36      nativeReduce       = ArrayProto.reduce,
37      nativeReduceRight  = ArrayProto.reduceRight,
38      nativeFilter       = ArrayProto.filter,
39      nativeEvery        = ArrayProto.every,
40      nativeSome         = ArrayProto.some,
41      nativeIndexOf      = ArrayProto.indexOf,
42      nativeLastIndexOf  = ArrayProto.lastIndexOf,
43      nativeIsArray      = Array.isArray,
44      nativeKeys         = Object.keys,
45      nativeBind         = FuncProto.bind;
46  
47    // Create a safe reference to the Underscore object for use below.
48    var _ = function(obj) {
49      if (obj instanceof _) return obj;
50      if (!(this instanceof _)) return new _(obj);
51      this._wrapped = obj;
52    };
53  
54    // Export the Underscore object for **Node.js**, with
55    // backwards-compatibility for the old `require()` API. If we're in
56    // the browser, add `_` as a global object via a string identifier,
57    // for Closure Compiler "advanced" mode.
58    if (typeof exports !== 'undefined') {
59      if (typeof module !== 'undefined' && module.exports) {
60        exports = module.exports = _;
61      }
62      exports._ = _;
63    } else {
64      root['_'] = _;
65    }
66  
67    // Current version.
68    _.VERSION = '1.4.1';
69  
70    // Collection Functions
71    // --------------------
72  
73    // The cornerstone, an `each` implementation, aka `forEach`.
74    // Handles objects with the built-in `forEach`, arrays, and raw objects.
75    // Delegates to **ECMAScript 5**'s native `forEach` if available.
76    var each = _.each = _.forEach = function(obj, iterator, context) {
77      if (nativeForEach && obj.forEach === nativeForEach) {
78        obj.forEach(iterator, context);
79      } else if (obj.length === +obj.length) {
80        for (var i = 0, l = obj.length; i < l; i++) {
81          if (iterator.call(context, obj[i], i, obj) === breaker) return;
82        }
83      } else {
84        for (var key in obj) {
85          if (_.has(obj, key)) {
86            if (iterator.call(context, obj[key], key, obj) === breaker) return;
87          }
88        }
89      }
90    };
91  
92    // Return the results of applying the iterator to each element.
93    // Delegates to **ECMAScript 5**'s native `map` if available.
94    _.map = _.collect = function(obj, iterator, context) {
95      var results = [];
96      if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
97      each(obj, function(value, index, list) {
98        results[results.length] = iterator.call(context, value, index, list);
99      });
100      return results;
101    };
102  
103    // **Reduce** builds up a single result from a list of values, aka `inject`,
104    // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
105    _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
106      var initial = arguments.length > 2;
107      if (nativeReduce && obj.reduce === nativeReduce) {
108        if (context) iterator = _.bind(iterator, context);
109        return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
110      }
111      each(obj, function(value, index, list) {
112        if (!initial) {
113          memo = value;
114          initial = true;
115        } else {
116          memo = iterator.call(context, memo, value, index, list);
117        }
118      });
119      if (!initial) throw new TypeError('Reduce of empty array with no initial value');
120      return memo;
121    };
122  
123    // The right-associative version of reduce, also known as `foldr`.
124    // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
125    _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
126      var initial = arguments.length > 2;
127      if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
128        if (context) iterator = _.bind(iterator, context);
129        return arguments.length > 2 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
130      }
131      var length = obj.length;
132      if (length !== +length) {
133        var keys = _.keys(obj);
134        length = keys.length;
135      }
136      each(obj, function(value, index, list) {
137        index = keys ? keys[--length] : --length;
138        if (!initial) {
139          memo = obj[index];
140          initial = true;
141        } else {
142          memo = iterator.call(context, memo, obj[index], index, list);
143        }
144      });
145      if (!initial) throw new TypeError('Reduce of empty array with no initial value');
146      return memo;
147    };
148  
149    // Return the first value which passes a truth test. Aliased as `detect`.
150    _.find = _.detect = function(obj, iterator, context) {
151      var result;
152      any(obj, function(value, index, list) {
153        if (iterator.call(context, value, index, list)) {
154          result = value;
155          return true;
156        }
157      });
158      return result;
159    };
160  
161    // Return all the elements that pass a truth test.
162    // Delegates to **ECMAScript 5**'s native `filter` if available.
163    // Aliased as `select`.
164    _.filter = _.select = function(obj, iterator, context) {
165      var results = [];
166      if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
167      each(obj, function(value, index, list) {
168        if (iterator.call(context, value, index, list)) results[results.length] = value;
169      });
170      return results;
171    };
172  
173    // Return all the elements for which a truth test fails.
174    _.reject = function(obj, iterator, context) {
175      var results = [];
176      each(obj, function(value, index, list) {
177        if (!iterator.call(context, value, index, list)) results[results.length] = value;
178      });
179      return results;
180    };
181  
182    // Determine whether all of the elements match a truth test.
183    // Delegates to **ECMAScript 5**'s native `every` if available.
184    // Aliased as `all`.
185    _.every = _.all = function(obj, iterator, context) {
186      iterator || (iterator = _.identity);
187      var result = true;
188      if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
189      each(obj, function(value, index, list) {
190        if (!(result = result && iterator.call(context, value, index, list))) return breaker;
191      });
192      return !!result;
193    };
194  
195    // Determine if at least one element in the object matches a truth test.
196    // Delegates to **ECMAScript 5**'s native `some` if available.
197    // Aliased as `any`.
198    var any = _.some = _.any = function(obj, iterator, context) {
199      iterator || (iterator = _.identity);
200      var result = false;
201      if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
202      each(obj, function(value, index, list) {
203        if (result || (result = iterator.call(context, value, index, list))) return breaker;
204      });
205      return !!result;
206    };
207  
208    // Determine if the array or object contains a given value (using `===`).
209    // Aliased as `include`.
210    _.contains = _.include = function(obj, target) {
211      var found = false;
212      if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
213      found = any(obj, function(value) {
214        return value === target;
215      });
216      return found;
217    };
218  
219    // Invoke a method (with arguments) on every item in a collection.
220    _.invoke = function(obj, method) {
221      var args = slice.call(arguments, 2);
222      return _.map(obj, function(value) {
223        return (_.isFunction(method) ? method : value[method]).apply(value, args);
224      });
225    };
226  
227    // Convenience version of a common use case of `map`: fetching a property.
228    _.pluck = function(obj, key) {
229      return _.map(obj, function(value){ return value[key]; });
230    };
231  
232    // Convenience version of a common use case of `filter`: selecting only objects
233    // with specific `key:value` pairs.
234    _.where = function(obj, attrs) {
235      if (_.isEmpty(attrs)) return [];
236      return _.filter(obj, function(value) {
237        for (var key in attrs) {
238          if (attrs[key] !== value[key]) return false;
239        }
240        return true;
241      });
242    };
243  
244    // Return the maximum element or (element-based computation).
245    // Can't optimize arrays of integers longer than 65,535 elements.
246    // See: https://bugs.webkit.org/show_bug.cgi?id=80797
247    _.max = function(obj, iterator, context) {
248      if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
249        return Math.max.apply(Math, obj);
250      }
251      if (!iterator && _.isEmpty(obj)) return -Infinity;
252      var result = {computed : -Infinity};
253      each(obj, function(value, index, list) {
254        var computed = iterator ? iterator.call(context, value, index, list) : value;
255        computed >= result.computed && (result = {value : value, computed : computed});
256      });
257      return result.value;
258    };
259  
260    // Return the minimum element (or element-based computation).
261    _.min = function(obj, iterator, context) {
262      if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
263        return Math.min.apply(Math, obj);
264      }
265      if (!iterator && _.isEmpty(obj)) return Infinity;
266      var result = {computed : Infinity};
267      each(obj, function(value, index, list) {
268        var computed = iterator ? iterator.call(context, value, index, list) : value;
269        computed < result.computed && (result = {value : value, computed : computed});
270      });
271      return result.value;
272    };
273  
274    // Shuffle an array.
275    _.shuffle = function(obj) {
276      var rand;
277      var index = 0;
278      var shuffled = [];
279      each(obj, function(value) {
280        rand = _.random(index++);
281        shuffled[index - 1] = shuffled[rand];
282        shuffled[rand] = value;
283      });
284      return shuffled;
285    };
286  
287    // An internal function to generate lookup iterators.
288    var lookupIterator = function(value) {
289      return _.isFunction(value) ? value : function(obj){ return obj[value]; };
290    };
291  
292    // Sort the object's values by a criterion produced by an iterator.
293    _.sortBy = function(obj, value, context) {
294      var iterator = lookupIterator(value);
295      return _.pluck(_.map(obj, function(value, index, list) {
296        return {
297          value : value,
298          index : index,
299          criteria : iterator.call(context, value, index, list)
300        };
301      }).sort(function(left, right) {
302        var a = left.criteria;
303        var b = right.criteria;
304        if (a !== b) {
305          if (a > b || a === void 0) return 1;
306          if (a < b || b === void 0) return -1;
307        }
308        return left.index < right.index ? -1 : 1;
309      }), 'value');
310    };
311  
312    // An internal function used for aggregate "group by" operations.
313    var group = function(obj, value, context, behavior) {
314      var result = {};
315      var iterator = lookupIterator(value);
316      each(obj, function(value, index) {
317        var key = iterator.call(context, value, index, obj);
318        behavior(result, key, value);
319      });
320      return result;
321    };
322  
323    // Groups the object's values by a criterion. Pass either a string attribute
324    // to group by, or a function that returns the criterion.
325    _.groupBy = function(obj, value, context) {
326      return group(obj, value, context, function(result, key, value) {
327        (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
328      });
329    };
330  
331    // Counts instances of an object that group by a certain criterion. Pass
332    // either a string attribute to count by, or a function that returns the
333    // criterion.
334    _.countBy = function(obj, value, context) {
335      return group(obj, value, context, function(result, key, value) {
336        if (!_.has(result, key)) result[key] = 0;
337        result[key]++;
338      });
339    };
340  
341    // Use a comparator function to figure out the smallest index at which
342    // an object should be inserted so as to maintain order. Uses binary search.
343    _.sortedIndex = function(array, obj, iterator, context) {
344      iterator = iterator == null ? _.identity : lookupIterator(iterator);
345      var value = iterator.call(context, obj);
346      var low = 0, high = array.length;
347      while (low < high) {
348        var mid = (low + high) >>> 1;
349        iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
350      }
351      return low;
352    };
353  
354    // Safely convert anything iterable into a real, live array.
355    _.toArray = function(obj) {
356      if (!obj) return [];
357      if (obj.length === +obj.length) return slice.call(obj);
358      return _.values(obj);
359    };
360  
361    // Return the number of elements in an object.
362    _.size = function(obj) {
363      return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
364    };
365  
366    // Array Functions
367    // ---------------
368  
369    // Get the first element of an array. Passing **n** will return the first N
370    // values in the array. Aliased as `head` and `take`. The **guard** check
371    // allows it to work with `_.map`.
372    _.first = _.head = _.take = function(array, n, guard) {
373      return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
374    };
375  
376    // Returns everything but the last entry of the array. Especially useful on
377    // the arguments object. Passing **n** will return all the values in
378    // the array, excluding the last N. The **guard** check allows it to work with
379    // `_.map`.
380    _.initial = function(array, n, guard) {
381      return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
382    };
383  
384    // Get the last element of an array. Passing **n** will return the last N
385    // values in the array. The **guard** check allows it to work with `_.map`.
386    _.last = function(array, n, guard) {
387      if ((n != null) && !guard) {
388        return slice.call(array, Math.max(array.length - n, 0));
389      } else {
390        return array[array.length - 1];
391      }
392    };
393  
394    // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
395    // Especially useful on the arguments object. Passing an **n** will return
396    // the rest N values in the array. The **guard**
397    // check allows it to work with `_.map`.
398    _.rest = _.tail = _.drop = function(array, n, guard) {
399      return slice.call(array, (n == null) || guard ? 1 : n);
400    };
401  
402    // Trim out all falsy values from an array.
403    _.compact = function(array) {
404      return _.filter(array, function(value){ return !!value; });
405    };
406  
407    // Internal implementation of a recursive `flatten` function.
408    var flatten = function(input, shallow, output) {
409      each(input, function(value) {
410        if (_.isArray(value)) {
411          shallow ? push.apply(output, value) : flatten(value, shallow, output);
412        } else {
413          output.push(value);
414        }
415      });
416      return output;
417    };
418  
419    // Return a completely flattened version of an array.
420    _.flatten = function(array, shallow) {
421      return flatten(array, shallow, []);
422    };
423  
424    // Return a version of the array that does not contain the specified value(s).
425    _.without = function(array) {
426      return _.difference(array, slice.call(arguments, 1));
427    };
428  
429    // Produce a duplicate-free version of the array. If the array has already
430    // been sorted, you have the option of using a faster algorithm.
431    // Aliased as `unique`.
432    _.uniq = _.unique = function(array, isSorted, iterator, context) {
433      var initial = iterator ? _.map(array, iterator, context) : array;
434      var results = [];
435      var seen = [];
436      each(initial, function(value, index) {
437        if (isSorted ? (!index || seen[seen.length - 1] !== value) : !_.contains(seen, value)) {
438          seen.push(value);
439          results.push(array[index]);
440        }
441      });
442      return results;
443    };
444  
445    // Produce an array that contains the union: each distinct element from all of
446    // the passed-in arrays.
447    _.union = function() {
448      return _.uniq(concat.apply(ArrayProto, arguments));
449    };
450  
451    // Produce an array that contains every item shared between all the
452    // passed-in arrays.
453    _.intersection = function(array) {
454      var rest = slice.call(arguments, 1);
455      return _.filter(_.uniq(array), function(item) {
456        return _.every(rest, function(other) {
457          return _.indexOf(other, item) >= 0;
458        });
459      });
460    };
461  
462    // Take the difference between one array and a number of other arrays.
463    // Only the elements present in just the first array will remain.
464    _.difference = function(array) {
465      var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
466      return _.filter(array, function(value){ return !_.contains(rest, value); });
467    };
468  
469    // Zip together multiple lists into a single array -- elements that share
470    // an index go together.
471    _.zip = function() {
472      var args = slice.call(arguments);
473      var length = _.max(_.pluck(args, 'length'));
474      var results = new Array(length);
475      for (var i = 0; i < length; i++) {
476        results[i] = _.pluck(args, "" + i);
477      }
478      return results;
479    };
480  
481    // Converts lists into objects. Pass either a single array of `[key, value]`
482    // pairs, or two parallel arrays of the same length -- one of keys, and one of
483    // the corresponding values.
484    _.object = function(list, values) {
485      var result = {};
486      for (var i = 0, l = list.length; i < l; i++) {
487        if (values) {
488          result[list[i]] = values[i];
489        } else {
490          result[list[i][0]] = list[i][1];
491        }
492      }
493      return result;
494    };
495  
496    // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
497    // we need this function. Return the position of the first occurrence of an
498    // item in an array, or -1 if the item is not included in the array.
499    // Delegates to **ECMAScript 5**'s native `indexOf` if available.
500    // If the array is large and already in sort order, pass `true`
501    // for **isSorted** to use binary search.
502    _.indexOf = function(array, item, isSorted) {
503      var i = 0, l = array.length;
504      if (isSorted) {
505        if (typeof isSorted == 'number') {
506          i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
507        } else {
508          i = _.sortedIndex(array, item);
509          return array[i] === item ? i : -1;
510        }
511      }
512      if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
513      for (; i < l; i++) if (array[i] === item) return i;
514      return -1;
515    };
516  
517    // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
518    _.lastIndexOf = function(array, item, from) {
519      var hasIndex = from != null;
520      if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
521        return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
522      }
523      var i = (hasIndex ? from : array.length);
524      while (i--) if (array[i] === item) return i;
525      return -1;
526    };
527  
528    // Generate an integer Array containing an arithmetic progression. A port of
529    // the native Python `range()` function. See
530    // [the Python documentation](http://docs.python.org/library/functions.html#range).
531    _.range = function(start, stop, step) {
532      if (arguments.length <= 1) {
533        stop = start || 0;
534        start = 0;
535      }
536      step = arguments[2] || 1;
537  
538      var len = Math.max(Math.ceil((stop - start) / step), 0);
539      var idx = 0;
540      var range = new Array(len);
541  
542      while(idx < len) {
543        range[idx++] = start;
544        start += step;
545      }
546  
547      return range;
548    };
549  
550    // Function (ahem) Functions
551    // ------------------
552  
553    // Reusable constructor function for prototype setting.
554    var ctor = function(){};
555  
556    // Create a function bound to a given object (assigning `this`, and arguments,
557    // optionally). Binding with arguments is also known as `curry`.
558    // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
559    // We check for `func.bind` first, to fail fast when `func` is undefined.
560    _.bind = function bind(func, context) {
561      var bound, args;
562      if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
563      if (!_.isFunction(func)) throw new TypeError;
564      args = slice.call(arguments, 2);
565      return bound = function() {
566        if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
567        ctor.prototype = func.prototype;
568        var self = new ctor;
569        var result = func.apply(self, args.concat(slice.call(arguments)));
570        if (Object(result) === result) return result;
571        return self;
572      };
573    };
574  
575    // Bind all of an object's methods to that object. Useful for ensuring that
576    // all callbacks defined on an object belong to it.
577    _.bindAll = function(obj) {
578      var funcs = slice.call(arguments, 1);
579      if (funcs.length == 0) funcs = _.functions(obj);
580      each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
581      return obj;
582    };
583  
584    // Memoize an expensive function by storing its results.
585    _.memoize = function(func, hasher) {
586      var memo = {};
587      hasher || (hasher = _.identity);
588      return function() {
589        var key = hasher.apply(this, arguments);
590        return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
591      };
592    };
593  
594    // Delays a function for the given number of milliseconds, and then calls
595    // it with the arguments supplied.
596    _.delay = function(func, wait) {
597      var args = slice.call(arguments, 2);
598      return setTimeout(function(){ return func.apply(null, args); }, wait);
599    };
600  
601    // Defers a function, scheduling it to run after the current call stack has
602    // cleared.
603    _.defer = function(func) {
604      return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
605    };
606  
607    // Returns a function, that, when invoked, will only be triggered at most once
608    // during a given window of time.
609    _.throttle = function(func, wait) {
610      var context, args, timeout, throttling, more, result;
611      var whenDone = _.debounce(function(){ more = throttling = false; }, wait);
612      return function() {
613        context = this; args = arguments;
614        var later = function() {
615          timeout = null;
616          if (more) {
617            result = func.apply(context, args);
618          }
619          whenDone();
620        };
621        if (!timeout) timeout = setTimeout(later, wait);
622        if (throttling) {
623          more = true;
624        } else {
625          throttling = true;
626          result = func.apply(context, args);
627        }
628        whenDone();
629        return result;
630      };
631    };
632  
633    // Returns a function, that, as long as it continues to be invoked, will not
634    // be triggered. The function will be called after it stops being called for
635    // N milliseconds. If `immediate` is passed, trigger the function on the
636    // leading edge, instead of the trailing.
637    _.debounce = function(func, wait, immediate) {
638      var timeout, result;
639      return function() {
640        var context = this, args = arguments;
641        var later = function() {
642          timeout = null;
643          if (!immediate) result = func.apply(context, args);
644        };
645        var callNow = immediate && !timeout;
646        clearTimeout(timeout);
647        timeout = setTimeout(later, wait);
648        if (callNow) result = func.apply(context, args);
649        return result;
650      };
651    };
652  
653    // Returns a function that will be executed at most one time, no matter how
654    // often you call it. Useful for lazy initialization.
655    _.once = function(func) {
656      var ran = false, memo;
657      return function() {
658        if (ran) return memo;
659        ran = true;
660        memo = func.apply(this, arguments);
661        func = null;
662        return memo;
663      };
664    };
665  
666    // Returns the first function passed as an argument to the second,
667    // allowing you to adjust arguments, run code before and after, and
668    // conditionally execute the original function.
669    _.wrap = function(func, wrapper) {
670      return function() {
671        var args = [func];
672        push.apply(args, arguments);
673        return wrapper.apply(this, args);
674      };
675    };
676  
677    // Returns a function that is the composition of a list of functions, each
678    // consuming the return value of the function that follows.
679    _.compose = function() {
680      var funcs = arguments;
681      return function() {
682        var args = arguments;
683        for (var i = funcs.length - 1; i >= 0; i--) {
684          args = [funcs[i].apply(this, args)];
685        }
686        return args[0];
687      };
688    };
689  
690    // Returns a function that will only be executed after being called N times.
691    _.after = function(times, func) {
692      if (times <= 0) return func();
693      return function() {
694        if (--times < 1) {
695          return func.apply(this, arguments);
696        }
697      };
698    };
699  
700    // Object Functions
701    // ----------------
702  
703    // Retrieve the names of an object's properties.
704    // Delegates to **ECMAScript 5**'s native `Object.keys`
705    _.keys = nativeKeys || function(obj) {
706      if (obj !== Object(obj)) throw new TypeError('Invalid object');
707      var keys = [];
708      for (var key in obj) if (_.has(obj, key)) keys[keys.length] = key;
709      return keys;
710    };
711  
712    // Retrieve the values of an object's properties.
713    _.values = function(obj) {
714      var values = [];
715      for (var key in obj) if (_.has(obj, key)) values.push(obj[key]);
716      return values;
717    };
718  
719    // Convert an object into a list of `[key, value]` pairs.
720    _.pairs = function(obj) {
721      var pairs = [];
722      for (var key in obj) if (_.has(obj, key)) pairs.push([key, obj[key]]);
723      return pairs;
724    };
725  
726    // Invert the keys and values of an object. The values must be serializable.
727    _.invert = function(obj) {
728      var result = {};
729      for (var key in obj) if (_.has(obj, key)) result[obj[key]] = key;
730      return result;
731    };
732  
733    // Return a sorted list of the function names available on the object.
734    // Aliased as `methods`
735    _.functions = _.methods = function(obj) {
736      var names = [];
737      for (var key in obj) {
738        if (_.isFunction(obj[key])) names.push(key);
739      }
740      return names.sort();
741    };
742  
743    // Extend a given object with all the properties in passed-in object(s).
744    _.extend = function(obj) {
745      each(slice.call(arguments, 1), function(source) {
746        for (var prop in source) {
747          obj[prop] = source[prop];
748        }
749      });
750      return obj;
751    };
752  
753    // Return a copy of the object only containing the whitelisted properties.
754    _.pick = function(obj) {
755      var copy = {};
756      var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
757      each(keys, function(key) {
758        if (key in obj) copy[key] = obj[key];
759      });
760      return copy;
761    };
762  
763     // Return a copy of the object without the blacklisted properties.
764    _.omit = function(obj) {
765      var copy = {};
766      var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
767      for (var key in obj) {
768        if (!_.contains(keys, key)) copy[key] = obj[key];
769      }
770      return copy;
771    };
772  
773    // Fill in a given object with default properties.
774    _.defaults = function(obj) {
775      each(slice.call(arguments, 1), function(source) {
776        for (var prop in source) {
777          if (obj[prop] == null) obj[prop] = source[prop];
778        }
779      });
780      return obj;
781    };
782  
783    // Create a (shallow-cloned) duplicate of an object.
784    _.clone = function(obj) {
785      if (!_.isObject(obj)) return obj;
786      return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
787    };
788  
789    // Invokes interceptor with the obj, and then returns obj.
790    // The primary purpose of this method is to "tap into" a method chain, in
791    // order to perform operations on intermediate results within the chain.
792    _.tap = function(obj, interceptor) {
793      interceptor(obj);
794      return obj;
795    };
796  
797    // Internal recursive comparison function for `isEqual`.
798    var eq = function(a, b, aStack, bStack) {
799      // Identical objects are equal. `0 === -0`, but they aren't identical.
800      // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.
801      if (a === b) return a !== 0 || 1 / a == 1 / b;
802      // A strict comparison is necessary because `null == undefined`.
803      if (a == null || b == null) return a === b;
804      // Unwrap any wrapped objects.
805      if (a instanceof _) a = a._wrapped;
806      if (b instanceof _) b = b._wrapped;
807      // Compare `[[Class]]` names.
808      var className = toString.call(a);
809      if (className != toString.call(b)) return false;
810      switch (className) {
811        // Strings, numbers, dates, and booleans are compared by value.
812        case '[object String]':
813          // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
814          // equivalent to `new String("5")`.
815          return a == String(b);
816        case '[object Number]':
817          // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
818          // other numeric values.
819          return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
820        case '[object Date]':
821        case '[object Boolean]':
822          // Coerce dates and booleans to numeric primitive values. Dates are compared by their
823          // millisecond representations. Note that invalid dates with millisecond representations
824          // of `NaN` are not equivalent.
825          return +a == +b;
826        // RegExps are compared by their source patterns and flags.
827        case '[object RegExp]':
828          return a.source == b.source &&
829                 a.global == b.global &&
830                 a.multiline == b.multiline &&
831                 a.ignoreCase == b.ignoreCase;
832      }
833      if (typeof a != 'object' || typeof b != 'object') return false;
834      // Assume equality for cyclic structures. The algorithm for detecting cyclic
835      // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
836      var length = aStack.length;
837      while (length--) {
838        // Linear search. Performance is inversely proportional to the number of
839        // unique nested structures.
840        if (aStack[length] == a) return bStack[length] == b;
841      }
842      // Add the first object to the stack of traversed objects.
843      aStack.push(a);
844      bStack.push(b);
845      var size = 0, result = true;
846      // Recursively compare objects and arrays.
847      if (className == '[object Array]') {
848        // Compare array lengths to determine if a deep comparison is necessary.
849        size = a.length;
850        result = size == b.length;
851        if (result) {
852          // Deep compare the contents, ignoring non-numeric properties.
853          while (size--) {
854            if (!(result = eq(a[size], b[size], aStack, bStack))) break;
855          }
856        }
857      } else {
858        // Objects with different constructors are not equivalent, but `Object`s
859        // from different frames are.
860        var aCtor = a.constructor, bCtor = b.constructor;
861        if (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor instanceof aCtor) &&
862                                 _.isFunction(bCtor) && (bCtor instanceof bCtor))) {
863          return false;
864        }
865        // Deep compare objects.
866        for (var key in a) {
867          if (_.has(a, key)) {
868            // Count the expected number of properties.
869            size++;
870            // Deep compare each member.
871            if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
872          }
873        }
874        // Ensure that both objects contain the same number of properties.
875        if (result) {
876          for (key in b) {
877            if (_.has(b, key) && !(size--)) break;
878          }
879          result = !size;
880        }
881      }
882      // Remove the first object from the stack of traversed objects.
883      aStack.pop();
884      bStack.pop();
885      return result;
886    };
887  
888    // Perform a deep comparison to check if two objects are equal.
889    _.isEqual = function(a, b) {
890      return eq(a, b, [], []);
891    };
892  
893    // Is a given array, string, or object empty?
894    // An "empty" object has no enumerable own-properties.
895    _.isEmpty = function(obj) {
896      if (obj == null) return true;
897      if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
898      for (var key in obj) if (_.has(obj, key)) return false;
899      return true;
900    };
901  
902    // Is a given value a DOM element?
903    _.isElement = function(obj) {
904      return !!(obj && obj.nodeType === 1);
905    };
906  
907    // Is a given value an array?
908    // Delegates to ECMA5's native Array.isArray
909    _.isArray = nativeIsArray || function(obj) {
910      return toString.call(obj) == '[object Array]';
911    };
912  
913    // Is a given variable an object?
914    _.isObject = function(obj) {
915      return obj === Object(obj);
916    };
917  
918    // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
919    each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
920      _['is' + name] = function(obj) {
921        return toString.call(obj) == '[object ' + name + ']';
922      };
923    });
924  
925    // Define a fallback version of the method in browsers (ahem, IE), where
926    // there isn't any inspectable "Arguments" type.
927    if (!_.isArguments(arguments)) {
928      _.isArguments = function(obj) {
929        return !!(obj && _.has(obj, 'callee'));
930      };
931    }
932  
933    // Optimize `isFunction` if appropriate.
934    if (typeof (/./) !== 'function') {
935      _.isFunction = function(obj) {
936        return typeof obj === 'function';
937      };
938    }
939  
940    // Is a given object a finite number?
941    _.isFinite = function(obj) {
942      return _.isNumber(obj) && isFinite(obj);
943    };
944  
945    // Is the given value `NaN`? (NaN is the only number which does not equal itself).
946    _.isNaN = function(obj) {
947      return _.isNumber(obj) && obj != +obj;
948    };
949  
950    // Is a given value a boolean?
951    _.isBoolean = function(obj) {
952      return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
953    };
954  
955    // Is a given value equal to null?
956    _.isNull = function(obj) {
957      return obj === null;
958    };
959  
960    // Is a given variable undefined?
961    _.isUndefined = function(obj) {
962      return obj === void 0;
963    };
964  
965    // Shortcut function for checking if an object has a given property directly
966    // on itself (in other words, not on a prototype).
967    _.has = function(obj, key) {
968      return hasOwnProperty.call(obj, key);
969    };
970  
971    // Utility Functions
972    // -----------------
973  
974    // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
975    // previous owner. Returns a reference to the Underscore object.
976    _.noConflict = function() {
977      root._ = previousUnderscore;
978      return this;
979    };
980  
981    // Keep the identity function around for default iterators.
982    _.identity = function(value) {
983      return value;
984    };
985  
986    // Run a function **n** times.
987    _.times = function(n, iterator, context) {
988      for (var i = 0; i < n; i++) iterator.call(context, i);
989    };
990  
991    // Return a random integer between min and max (inclusive).
992    _.random = function(min, max) {
993      if (max == null) {
994        max = min;
995        min = 0;
996      }
997      return min + (0 | Math.random() * (max - min + 1));
998    };
999  
1000    // List of HTML entities for escaping.
1001    var entityMap = {
1002      escape: {
1003        '&': '&amp;',
1004        '<': '<',
1005        '>': '>',
1006        '"': '&quot;',
1007        "'": '&#x27;',
1008        '/': '&#x2F;'
1009      }
1010    };
1011    entityMap.unescape = _.invert(entityMap.escape);
1012  
1013    // Regexes containing the keys and values listed immediately above.
1014    var entityRegexes = {
1015      escape:   new RegExp('[' + _.keys(entityMap.escape).join('') + ']', 'g'),
1016      unescape: new RegExp('(' + _.keys(entityMap.unescape).join('|') + ')', 'g')
1017    };
1018  
1019    // Functions for escaping and unescaping strings to/from HTML interpolation.
1020    _.each(['escape', 'unescape'], function(method) {
1021      _[method] = function(string) {
1022        if (string == null) return '';
1023        return ('' + string).replace(entityRegexes[method], function(match) {
1024          return entityMap[method][match];
1025        });
1026      };
1027    });
1028  
1029    // If the value of the named property is a function then invoke it;
1030    // otherwise, return it.
1031    _.result = function(object, property) {
1032      if (object == null) return null;
1033      var value = object[property];
1034      return _.isFunction(value) ? value.call(object) : value;
1035    };
1036  
1037    // Add your own custom functions to the Underscore object.
1038    _.mixin = function(obj) {
1039      each(_.functions(obj), function(name){
1040        var func = _[name] = obj[name];
1041        _.prototype[name] = function() {
1042          var args = [this._wrapped];
1043          push.apply(args, arguments);
1044          return result.call(this, func.apply(_, args));
1045        };
1046      });
1047    };
1048  
1049    // Generate a unique integer id (unique within the entire client session).
1050    // Useful for temporary DOM ids.
1051    var idCounter = 0;
1052    _.uniqueId = function(prefix) {
1053      var id = idCounter++;
1054      return prefix ? prefix + id : id;
1055    };
1056  
1057    // By default, Underscore uses ERB-style template delimiters, change the
1058    // following template settings to use alternative delimiters.
1059    _.templateSettings = {
1060      evaluate    : /<%([\s\S]+?)%>/g,
1061      interpolate : /<%=([\s\S]+?)%>/g,
1062      escape      : /<%-([\s\S]+?)%>/g
1063    };
1064  
1065    // When customizing `templateSettings`, if you don't want to define an
1066    // interpolation, evaluation or escaping regex, we need one that is
1067    // guaranteed not to match.
1068    var noMatch = /(.)^/;
1069  
1070    // Certain characters need to be escaped so that they can be put into a
1071    // string literal.
1072    var escapes = {
1073      "'":      "'",
1074      '\\':     '\\',
1075      '\r':     'r',
1076      '\n':     'n',
1077      '\t':     't',
1078      '\u2028': 'u2028',
1079      '\u2029': 'u2029'
1080    };
1081  
1082    var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
1083  
1084    // JavaScript micro-templating, similar to John Resig's implementation.
1085    // Underscore templating handles arbitrary delimiters, preserves whitespace,
1086    // and correctly escapes quotes within interpolated code.
1087    _.template = function(text, data, settings) {
1088      settings = _.defaults({}, settings, _.templateSettings);
1089  
1090      // Combine delimiters into one regular expression via alternation.
1091      var matcher = new RegExp([
1092        (settings.escape || noMatch).source,
1093        (settings.interpolate || noMatch).source,
1094        (settings.evaluate || noMatch).source
1095      ].join('|') + '|$', 'g');
1096  
1097      // Compile the template source, escaping string literals appropriately.
1098      var index = 0;
1099      var source = "__p+='";
1100      text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
1101        source += text.slice(index, offset)
1102          .replace(escaper, function(match) { return '\\' + escapes[match]; });
1103        source +=
1104          escape ? "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'" :
1105          interpolate ? "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'" :
1106          evaluate ? "';\n" + evaluate + "\n__p+='" : '';
1107        index = offset + match.length;
1108      });
1109      source += "';\n";
1110  
1111      // If a variable is not specified, place data values in local scope.
1112      if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
1113  
1114      source = "var __t,__p='',__j=Array.prototype.join," +
1115        "print=function(){__p+=__j.call(arguments,'');};\n" +
1116        source + "return __p;\n";
1117  
1118      try {
1119        var render = new Function(settings.variable || 'obj', '_', source);
1120      } catch (e) {
1121        e.source = source;
1122        throw e;
1123      }
1124  
1125      if (data) return render(data, _);
1126      var template = function(data) {
1127        return render.call(this, data, _);
1128      };
1129  
1130      // Provide the compiled function source as a convenience for precompilation.
1131      template.source = 'function(' + (settings.variable || 'obj') + '){\n' + source + '}';
1132  
1133      return template;
1134    };
1135  
1136    // Add a "chain" function, which will delegate to the wrapper.
1137    _.chain = function(obj) {
1138      return _(obj).chain();
1139    };
1140  
1141    // OOP
1142    // ---------------
1143    // If Underscore is called as a function, it returns a wrapped object that
1144    // can be used OO-style. This wrapper holds altered versions of all the
1145    // underscore functions. Wrapped objects may be chained.
1146  
1147    // Helper function to continue chaining intermediate results.
1148    var result = function(obj) {
1149      return this._chain ? _(obj).chain() : obj;
1150    };
1151  
1152    // Add all of the Underscore functions to the wrapper object.
1153    _.mixin(_);
1154  
1155    // Add all mutator Array functions to the wrapper.
1156    each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
1157      var method = ArrayProto[name];
1158      _.prototype[name] = function() {
1159        var obj = this._wrapped;
1160        method.apply(obj, arguments);
1161        if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
1162        return result.call(this, obj);
1163      };
1164    });
1165  
1166    // Add all accessor Array functions to the wrapper.
1167    each(['concat', 'join', 'slice'], function(name) {
1168      var method = ArrayProto[name];
1169      _.prototype[name] = function() {
1170        return result.call(this, method.apply(this._wrapped, arguments));
1171      };
1172    });
1173  
1174    _.extend(_.prototype, {
1175  
1176      // Start chaining a wrapped Underscore object.
1177      chain: function() {
1178        this._chain = true;
1179        return this;
1180      },
1181  
1182      // Extracts the result from a wrapped and chained object.
1183      value: function() {
1184        return this._wrapped;
1185      }
1186  
1187    });
1188  
1189  }).call(this);
//     Underscore.js 1.4.1
2  //     http://underscorejs.org
3  //     (c) 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.
4  //     Underscore may be freely distributed under the MIT license.
5  
6  (function() {
7  
8    // Baseline setup
9    // --------------
10  
11    // Establish the root object, `window` in the browser, or `global` on the server.
12    var root = this;
13  
14    // Save the previous value of the `_` variable.
15    var previousUnderscore = root._;
16  
17    // Establish the object that gets returned to break out of a loop iteration.
18    var breaker = {};
19  
20    // Save bytes in the minified (but not gzipped) version:
21    var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
22  
23    // Create quick reference variables for speed access to core prototypes.
24    var push             = ArrayProto.push,
25        slice            = ArrayProto.slice,
26        concat           = ArrayProto.concat,
27        unshift          = ArrayProto.unshift,
28        toString         = ObjProto.toString,
29        hasOwnProperty   = ObjProto.hasOwnProperty;
30  
31    // All **ECMAScript 5** native function implementations that we hope to use
32    // are declared here.
33    var
34      nativeForEach      = ArrayProto.forEach,
35      nativeMap          = ArrayProto.map,
36      nativeReduce       = ArrayProto.reduce,
37      nativeReduceRight  = ArrayProto.reduceRight,
38      nativeFilter       = ArrayProto.filter,
39      nativeEvery        = ArrayProto.every,
40      nativeSome         = ArrayProto.some,
41      nativeIndexOf      = ArrayProto.indexOf,
42      nativeLastIndexOf  = ArrayProto.lastIndexOf,
43      nativeIsArray      = Array.isArray,
44      nativeKeys         = Object.keys,
45      nativeBind         = FuncProto.bind;
46  
47    // Create a safe reference to the Underscore object for use below.
48    var _ = function(obj) {
49      if (obj instanceof _) return obj;
50      if (!(this instanceof _)) return new _(obj);
51      this._wrapped = obj;
52    };
53  
54    // Export the Underscore object for **Node.js**, with
55    // backwards-compatibility for the old `require()` API. If we're in
56    // the browser, add `_` as a global object via a string identifier,
57    // for Closure Compiler "advanced" mode.
58    if (typeof exports !== 'undefined') {
59      if (typeof module !== 'undefined' && module.exports) {
60        exports = module.exports = _;
61      }
62      exports._ = _;
63    } else {
64      root['_'] = _;
65    }
66  
67    // Current version.
68    _.VERSION = '1.4.1';
69  
70    // Collection Functions
71    // --------------------
72  
73    // The cornerstone, an `each` implementation, aka `forEach`.
74    // Handles objects with the built-in `forEach`, arrays, and raw objects.
75    // Delegates to **ECMAScript 5**'s native `forEach` if available.
76    var each = _.each = _.forEach = function(obj, iterator, context) {
77      if (nativeForEach && obj.forEach === nativeForEach) {
78        obj.forEach(iterator, context);
79      } else if (obj.length === +obj.length) {
80        for (var i = 0, l = obj.length; i < l; i++) {
81          if (iterator.call(context, obj[i], i, obj) === breaker) return;
82        }
83      } else {
84        for (var key in obj) {
85          if (_.has(obj, key)) {
86            if (iterator.call(context, obj[key], key, obj) === breaker) return;
87          }
88        }
89      }
90    };
91  
92    // Return the results of applying the iterator to each element.
93    // Delegates to **ECMAScript 5**'s native `map` if available.
94    _.map = _.collect = function(obj, iterator, context) {
95      var results = [];
96      if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
97      each(obj, function(value, index, list) {
98        results[results.length] = iterator.call(context, value, index, list);
99      });
100      return results;
101    };
102  
103    // **Reduce** builds up a single result from a list of values, aka `inject`,
104    // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
105    _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
106      var initial = arguments.length > 2;
107      if (nativeReduce && obj.reduce === nativeReduce) {
108        if (context) iterator = _.bind(iterator, context);
109        return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
110      }
111      each(obj, function(value, index, list) {
112        if (!initial) {
113          memo = value;
114          initial = true;
115        } else {
116          memo = iterator.call(context, memo, value, index, list);
117        }
118      });
119      if (!initial) throw new TypeError('Reduce of empty array with no initial value');
120      return memo;
121    };
122  
123    // The right-associative version of reduce, also known as `foldr`.
124    // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
125    _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
126      var initial = arguments.length > 2;
127      if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
128        if (context) iterator = _.bind(iterator, context);
129        return arguments.length > 2 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
130      }
131      var length = obj.length;
132      if (length !== +length) {
133        var keys = _.keys(obj);
134        length = keys.length;
135      }
136      each(obj, function(value, index, list) {
137        index = keys ? keys[--length] : --length;
138        if (!initial) {
139          memo = obj[index];
140          initial = true;
141        } else {
142          memo = iterator.call(context, memo, obj[index], index, list);
143        }
144      });
145      if (!initial) throw new TypeError('Reduce of empty array with no initial value');
146      return memo;
147    };
148  
149    // Return the first value which passes a truth test. Aliased as `detect`.
150    _.find = _.detect = function(obj, iterator, context) {
151      var result;
152      any(obj, function(value, index, list) {
153        if (iterator.call(context, value, index, list)) {
154          result = value;
155          return true;
156        }
157      });
158      return result;
159    };
160  
161    // Return all the elements that pass a truth test.
162    // Delegates to **ECMAScript 5**'s native `filter` if available.
163    // Aliased as `select`.
164    _.filter = _.select = function(obj, iterator, context) {
165      var results = [];
166      if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
167      each(obj, function(value, index, list) {
168        if (iterator.call(context, value, index, list)) results[results.length] = value;
169      });
170      return results;
171    };
172  
173    // Return all the elements for which a truth test fails.
174    _.reject = function(obj, iterator, context) {
175      var results = [];
176      each(obj, function(value, index, list) {
177        if (!iterator.call(context, value, index, list)) results[results.length] = value;
178      });
179      return results;
180    };
181  
182    // Determine whether all of the elements match a truth test.
183    // Delegates to **ECMAScript 5**'s native `every` if available.
184    // Aliased as `all`.
185    _.every = _.all = function(obj, iterator, context) {
186      iterator || (iterator = _.identity);
187      var result = true;
188      if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
189      each(obj, function(value, index, list) {
190        if (!(result = result && iterator.call(context, value, index, list))) return breaker;
191      });
192      return !!result;
193    };
194  
195    // Determine if at least one element in the object matches a truth test.
196    // Delegates to **ECMAScript 5**'s native `some` if available.
197    // Aliased as `any`.
198    var any = _.some = _.any = function(obj, iterator, context) {
199      iterator || (iterator = _.identity);
200      var result = false;
201      if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
202      each(obj, function(value, index, list) {
203        if (result || (result = iterator.call(context, value, index, list))) return breaker;
204      });
205      return !!result;
206    };
207  
208    // Determine if the array or object contains a given value (using `===`).
209    // Aliased as `include`.
210    _.contains = _.include = function(obj, target) {
211      var found = false;
212      if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
213      found = any(obj, function(value) {
214        return value === target;
215      });
216      return found;
217    };
218  
219    // Invoke a method (with arguments) on every item in a collection.
220    _.invoke = function(obj, method) {
221      var args = slice.call(arguments, 2);
222      return _.map(obj, function(value) {
223        return (_.isFunction(method) ? method : value[method]).apply(value, args);
224      });
225    };
226  
227    // Convenience version of a common use case of `map`: fetching a property.
228    _.pluck = function(obj, key) {
229      return _.map(obj, function(value){ return value[key]; });
230    };
231  
232    // Convenience version of a common use case of `filter`: selecting only objects
233    // with specific `key:value` pairs.
234    _.where = function(obj, attrs) {
235      if (_.isEmpty(attrs)) return [];
236      return _.filter(obj, function(value) {
237        for (var key in attrs) {
238          if (attrs[key] !== value[key]) return false;
239        }
240        return true;
241      });
242    };
243  
244    // Return the maximum element or (element-based computation).
245    // Can't optimize arrays of integers longer than 65,535 elements.
246    // See: https://bugs.webkit.org/show_bug.cgi?id=80797
247    _.max = function(obj, iterator, context) {
248      if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
249        return Math.max.apply(Math, obj);
250      }
251      if (!iterator && _.isEmpty(obj)) return -Infinity;
252      var result = {computed : -Infinity};
253      each(obj, function(value, index, list) {
254        var computed = iterator ? iterator.call(context, value, index, list) : value;
255        computed >= result.computed && (result = {value : value, computed : computed});
256      });
257      return result.value;
258    };
259  
260    // Return the minimum element (or element-based computation).
261    _.min = function(obj, iterator, context) {
262      if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
263        return Math.min.apply(Math, obj);
264      }
265      if (!iterator && _.isEmpty(obj)) return Infinity;
266      var result = {computed : Infinity};
267      each(obj, function(value, index, list) {
268        var computed = iterator ? iterator.call(context, value, index, list) : value;
269        computed < result.computed && (result = {value : value, computed : computed});
270      });
271      return result.value;
272    };
273  
274    // Shuffle an array.
275    _.shuffle = function(obj) {
276      var rand;
277      var index = 0;
278      var shuffled = [];
279      each(obj, function(value) {
280        rand = _.random(index++);
281        shuffled[index - 1] = shuffled[rand];
282        shuffled[rand] = value;
283      });
284      return shuffled;
285    };
286  
287    // An internal function to generate lookup iterators.
288    var lookupIterator = function(value) {
289      return _.isFunction(value) ? value : function(obj){ return obj[value]; };
290    };
291  
292    // Sort the object's values by a criterion produced by an iterator.
293    _.sortBy = function(obj, value, context) {
294      var iterator = lookupIterator(value);
295      return _.pluck(_.map(obj, function(value, index, list) {
296        return {
297          value : value,
298          index : index,
299          criteria : iterator.call(context, value, index, list)
300        };
301      }).sort(function(left, right) {
302        var a = left.criteria;
303        var b = right.criteria;
304        if (a !== b) {
305          if (a > b || a === void 0) return 1;
306          if (a < b || b === void 0) return -1;
307        }
308        return left.index < right.index ? -1 : 1;
309      }), 'value');
310    };
311  
312    // An internal function used for aggregate "group by" operations.
313    var group = function(obj, value, context, behavior) {
314      var result = {};
315      var iterator = lookupIterator(value);
316      each(obj, function(value, index) {
317        var key = iterator.call(context, value, index, obj);
318        behavior(result, key, value);
319      });
320      return result;
321    };
322  
323    // Groups the object's values by a criterion. Pass either a string attribute
324    // to group by, or a function that returns the criterion.
325    _.groupBy = function(obj, value, context) {
326      return group(obj, value, context, function(result, key, value) {
327        (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
328      });
329    };
330  
331    // Counts instances of an object that group by a certain criterion. Pass
332    // either a string attribute to count by, or a function that returns the
333    // criterion.
334    _.countBy = function(obj, value, context) {
335      return group(obj, value, context, function(result, key, value) {
336        if (!_.has(result, key)) result[key] = 0;
337        result[key]++;
338      });
339    };
340  
341    // Use a comparator function to figure out the smallest index at which
342    // an object should be inserted so as to maintain order. Uses binary search.
343    _.sortedIndex = function(array, obj, iterator, context) {
344      iterator = iterator == null ? _.identity : lookupIterator(iterator);
345      var value = iterator.call(context, obj);
346      var low = 0, high = array.length;
347      while (low < high) {
348        var mid = (low + high) >>> 1;
349        iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
350      }
351      return low;
352    };
353  
354    // Safely convert anything iterable into a real, live array.
355    _.toArray = function(obj) {
356      if (!obj) return [];
357      if (obj.length === +obj.length) return slice.call(obj);
358      return _.values(obj);
359    };
360  
361    // Return the number of elements in an object.
362    _.size = function(obj) {
363      return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
364    };
365  
366    // Array Functions
367    // ---------------
368  
369    // Get the first element of an array. Passing **n** will return the first N
370    // values in the array. Aliased as `head` and `take`. The **guard** check
371    // allows it to work with `_.map`.
372    _.first = _.head = _.take = function(array, n, guard) {
373      return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
374    };
375  
376    // Returns everything but the last entry of the array. Especially useful on
377    // the arguments object. Passing **n** will return all the values in
378    // the array, excluding the last N. The **guard** check allows it to work with
379    // `_.map`.
380    _.initial = function(array, n, guard) {
381      return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
382    };
383  
384    // Get the last element of an array. Passing **n** will return the last N
385    // values in the array. The **guard** check allows it to work with `_.map`.
386    _.last = function(array, n, guard) {
387      if ((n != null) && !guard) {
388        return slice.call(array, Math.max(array.length - n, 0));
389      } else {
390        return array[array.length - 1];
391      }
392    };
393  
394    // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
395    // Especially useful on the arguments object. Passing an **n** will return
396    // the rest N values in the array. The **guard**
397    // check allows it to work with `_.map`.
398    _.rest = _.tail = _.drop = function(array, n, guard) {
399      return slice.call(array, (n == null) || guard ? 1 : n);
400    };
401  
402    // Trim out all falsy values from an array.
403    _.compact = function(array) {
404      return _.filter(array, function(value){ return !!value; });
405    };
406  
407    // Internal implementation of a recursive `flatten` function.
408    var flatten = function(input, shallow, output) {
409      each(input, function(value) {
410        if (_.isArray(value)) {
411          shallow ? push.apply(output, value) : flatten(value, shallow, output);
412        } else {
413          output.push(value);
414        }
415      });
416      return output;
417    };
418  
419    // Return a completely flattened version of an array.
420    _.flatten = function(array, shallow) {
421      return flatten(array, shallow, []);
422    };
423  
424    // Return a version of the array that does not contain the specified value(s).
425    _.without = function(array) {
426      return _.difference(array, slice.call(arguments, 1));
427    };
428  
429    // Produce a duplicate-free version of the array. If the array has already
430    // been sorted, you have the option of using a faster algorithm.
431    // Aliased as `unique`.
432    _.uniq = _.unique = function(array, isSorted, iterator, context) {
433      var initial = iterator ? _.map(array, iterator, context) : array;
434      var results = [];
435      var seen = [];
436      each(initial, function(value, index) {
437        if (isSorted ? (!index || seen[seen.length - 1] !== value) : !_.contains(seen, value)) {
438          seen.push(value);
439          results.push(array[index]);
440        }
441      });
442      return results;
443    };
444  
445    // Produce an array that contains the union: each distinct element from all of
446    // the passed-in arrays.
447    _.union = function() {
448      return _.uniq(concat.apply(ArrayProto, arguments));
449    };
450  
451    // Produce an array that contains every item shared between all the
452    // passed-in arrays.
453    _.intersection = function(array) {
454      var rest = slice.call(arguments, 1);
455      return _.filter(_.uniq(array), function(item) {
456        return _.every(rest, function(other) {
457          return _.indexOf(other, item) >= 0;
458        });
459      });
460    };
461  
462    // Take the difference between one array and a number of other arrays.
463    // Only the elements present in just the first array will remain.
464    _.difference = function(array) {
465      var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
466      return _.filter(array, function(value){ return !_.contains(rest, value); });
467    };
468  
469    // Zip together multiple lists into a single array -- elements that share
470    // an index go together.
471    _.zip = function() {
472      var args = slice.call(arguments);
473      var length = _.max(_.pluck(args, 'length'));
474      var results = new Array(length);
475      for (var i = 0; i < length; i++) {
476        results[i] = _.pluck(args, "" + i);
477      }
478      return results;
479    };
480  
481    // Converts lists into objects. Pass either a single array of `[key, value]`
482    // pairs, or two parallel arrays of the same length -- one of keys, and one of
483    // the corresponding values.
484    _.object = function(list, values) {
485      var result = {};
486      for (var i = 0, l = list.length; i < l; i++) {
487        if (values) {
488          result[list[i]] = values[i];
489        } else {
490          result[list[i][0]] = list[i][1];
491        }
492      }
493      return result;
494    };
495  
496    // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
497    // we need this function. Return the position of the first occurrence of an
498    // item in an array, or -1 if the item is not included in the array.
499    // Delegates to **ECMAScript 5**'s native `indexOf` if available.
500    // If the array is large and already in sort order, pass `true`
501    // for **isSorted** to use binary search.
502    _.indexOf = function(array, item, isSorted) {
503      var i = 0, l = array.length;
504      if (isSorted) {
505        if (typeof isSorted == 'number') {
506          i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
507        } else {
508          i = _.sortedIndex(array, item);
509          return array[i] === item ? i : -1;
510        }
511      }
512      if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
513      for (; i < l; i++) if (array[i] === item) return i;
514      return -1;
515    };
516  
517    // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
518    _.lastIndexOf = function(array, item, from) {
519      var hasIndex = from != null;
520      if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
521        return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
522      }
523      var i = (hasIndex ? from : array.length);
524      while (i--) if (array[i] === item) return i;
525      return -1;
526    };
527  
528    // Generate an integer Array containing an arithmetic progression. A port of
529    // the native Python `range()` function. See
530    // [the Python documentation](http://docs.python.org/library/functions.html#range).
531    _.range = function(start, stop, step) {
532      if (arguments.length <= 1) {
533        stop = start || 0;
534        start = 0;
535      }
536      step = arguments[2] || 1;
537  
538      var len = Math.max(Math.ceil((stop - start) / step), 0);
539      var idx = 0;
540      var range = new Array(len);
541  
542      while(idx < len) {
543        range[idx++] = start;
544        start += step;
545      }
546  
547      return range;
548    };
549  
550    // Function (ahem) Functions
551    // ------------------
552  
553    // Reusable constructor function for prototype setting.
554    var ctor = function(){};
555  
556    // Create a function bound to a given object (assigning `this`, and arguments,
557    // optionally). Binding with arguments is also known as `curry`.
558    // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
559    // We check for `func.bind` first, to fail fast when `func` is undefined.
560    _.bind = function bind(func, context) {
561      var bound, args;
562      if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
563      if (!_.isFunction(func)) throw new TypeError;
564      args = slice.call(arguments, 2);
565      return bound = function() {
566        if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
567        ctor.prototype = func.prototype;
568        var self = new ctor;
569        var result = func.apply(self, args.concat(slice.call(arguments)));
570        if (Object(result) === result) return result;
571        return self;
572      };
573    };
574  
575    // Bind all of an object's methods to that object. Useful for ensuring that
576    // all callbacks defined on an object belong to it.
577    _.bindAll = function(obj) {
578      var funcs = slice.call(arguments, 1);
579      if (funcs.length == 0) funcs = _.functions(obj);
580      each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
581      return obj;
582    };
583  
584    // Memoize an expensive function by storing its results.
585    _.memoize = function(func, hasher) {
586      var memo = {};
587      hasher || (hasher = _.identity);
588      return function() {
589        var key = hasher.apply(this, arguments);
590        return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
591      };
592    };
593  
594    // Delays a function for the given number of milliseconds, and then calls
595    // it with the arguments supplied.
596    _.delay = function(func, wait) {
597      var args = slice.call(arguments, 2);
598      return setTimeout(function(){ return func.apply(null, args); }, wait);
599    };
600  
601    // Defers a function, scheduling it to run after the current call stack has
602    // cleared.
603    _.defer = function(func) {
604      return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
605    };
606  
607    // Returns a function, that, when invoked, will only be triggered at most once
608    // during a given window of time.
609    _.throttle = function(func, wait) {
610      var context, args, timeout, throttling, more, result;
611      var whenDone = _.debounce(function(){ more = throttling = false; }, wait);
612      return function() {
613        context = this; args = arguments;
614        var later = function() {
615          timeout = null;
616          if (more) {
617            result = func.apply(context, args);
618          }
619          whenDone();
620        };
621        if (!timeout) timeout = setTimeout(later, wait);
622        if (throttling) {
623          more = true;
624        } else {
625          throttling = true;
626          result = func.apply(context, args);
627        }
628        whenDone();
629        return result;
630      };
631    };
632  
633    // Returns a function, that, as long as it continues to be invoked, will not
634    // be triggered. The function will be called after it stops being called for
635    // N milliseconds. If `immediate` is passed, trigger the function on the
636    // leading edge, instead of the trailing.
637    _.debounce = function(func, wait, immediate) {
638      var timeout, result;
639      return function() {
640        var context = this, args = arguments;
641        var later = function() {
642          timeout = null;
643          if (!immediate) result = func.apply(context, args);
644        };
645        var callNow = immediate && !timeout;
646        clearTimeout(timeout);
647        timeout = setTimeout(later, wait);
648        if (callNow) result = func.apply(context, args);
649        return result;
650      };
651    };
652  
653    // Returns a function that will be executed at most one time, no matter how
654    // often you call it. Useful for lazy initialization.
655    _.once = function(func) {
656      var ran = false, memo;
657      return function() {
658        if (ran) return memo;
659        ran = true;
660        memo = func.apply(this, arguments);
661        func = null;
662        return memo;
663      };
664    };
665  
666    // Returns the first function passed as an argument to the second,
667    // allowing you to adjust arguments, run code before and after, and
668    // conditionally execute the original function.
669    _.wrap = function(func, wrapper) {
670      return function() {
671        var args = [func];
672        push.apply(args, arguments);
673        return wrapper.apply(this, args);
674      };
675    };
676  
677    // Returns a function that is the composition of a list of functions, each
678    // consuming the return value of the function that follows.
679    _.compose = function() {
680      var funcs = arguments;
681      return function() {
682        var args = arguments;
683        for (var i = funcs.length - 1; i >= 0; i--) {
684          args = [funcs[i].apply(this, args)];
685        }
686        return args[0];
687      };
688    };
689  
690    // Returns a function that will only be executed after being called N times.
691    _.after = function(times, func) {
692      if (times <= 0) return func();
693      return function() {
694        if (--times < 1) {
695          return func.apply(this, arguments);
696        }
697      };
698    };
699  
700    // Object Functions
701    // ----------------
702  
703    // Retrieve the names of an object's properties.
704    // Delegates to **ECMAScript 5**'s native `Object.keys`
705    _.keys = nativeKeys || function(obj) {
706      if (obj !== Object(obj)) throw new TypeError('Invalid object');
707      var keys = [];
708      for (var key in obj) if (_.has(obj, key)) keys[keys.length] = key;
709      return keys;
710    };
711  
712    // Retrieve the values of an object's properties.
713    _.values = function(obj) {
714      var values = [];
715      for (var key in obj) if (_.has(obj, key)) values.push(obj[key]);
716      return values;
717    };
718  
719    // Convert an object into a list of `[key, value]` pairs.
720    _.pairs = function(obj) {
721      var pairs = [];
722      for (var key in obj) if (_.has(obj, key)) pairs.push([key, obj[key]]);
723      return pairs;
724    };
725  
726    // Invert the keys and values of an object. The values must be serializable.
727    _.invert = function(obj) {
728      var result = {};
729      for (var key in obj) if (_.has(obj, key)) result[obj[key]] = key;
730      return result;
731    };
732  
733    // Return a sorted list of the function names available on the object.
734    // Aliased as `methods`
735    _.functions = _.methods = function(obj) {
736      var names = [];
737      for (var key in obj) {
738        if (_.isFunction(obj[key])) names.push(key);
739      }
740      return names.sort();
741    };
742  
743    // Extend a given object with all the properties in passed-in object(s).
744    _.extend = function(obj) {
745      each(slice.call(arguments, 1), function(source) {
746        for (var prop in source) {
747          obj[prop] = source[prop];
748        }
749      });
750      return obj;
751    };
752  
753    // Return a copy of the object only containing the whitelisted properties.
754    _.pick = function(obj) {
755      var copy = {};
756      var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
757      each(keys, function(key) {
758        if (key in obj) copy[key] = obj[key];
759      });
760      return copy;
761    };
762  
763     // Return a copy of the object without the blacklisted properties.
764    _.omit = function(obj) {
765      var copy = {};
766      var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
767      for (var key in obj) {
768        if (!_.contains(keys, key)) copy[key] = obj[key];
769      }
770      return copy;
771    };
772  
773    // Fill in a given object with default properties.
774    _.defaults = function(obj) {
775      each(slice.call(arguments, 1), function(source) {
776        for (var prop in source) {
777          if (obj[prop] == null) obj[prop] = source[prop];
778        }
779      });
780      return obj;
781    };
782  
783    // Create a (shallow-cloned) duplicate of an object.
784    _.clone = function(obj) {
785      if (!_.isObject(obj)) return obj;
786      return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
787    };
788  
789    // Invokes interceptor with the obj, and then returns obj.
790    // The primary purpose of this method is to "tap into" a method chain, in
791    // order to perform operations on intermediate results within the chain.
792    _.tap = function(obj, interceptor) {
793      interceptor(obj);
794      return obj;
795    };
796  
797    // Internal recursive comparison function for `isEqual`.
798    var eq = function(a, b, aStack, bStack) {
799      // Identical objects are equal. `0 === -0`, but they aren't identical.
800      // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.
801      if (a === b) return a !== 0 || 1 / a == 1 / b;
802      // A strict comparison is necessary because `null == undefined`.
803      if (a == null || b == null) return a === b;
804      // Unwrap any wrapped objects.
805      if (a instanceof _) a = a._wrapped;
806      if (b instanceof _) b = b._wrapped;
807      // Compare `[[Class]]` names.
808      var className = toString.call(a);
809      if (className != toString.call(b)) return false;
810      switch (className) {
811        // Strings, numbers, dates, and booleans are compared by value.
812        case '[object String]':
813          // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
814          // equivalent to `new String("5")`.
815          return a == String(b);
816        case '[object Number]':
817          // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
818          // other numeric values.
819          return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
820        case '[object Date]':
821        case '[object Boolean]':
822          // Coerce dates and booleans to numeric primitive values. Dates are compared by their
823          // millisecond representations. Note that invalid dates with millisecond representations
824          // of `NaN` are not equivalent.
825          return +a == +b;
826        // RegExps are compared by their source patterns and flags.
827        case '[object RegExp]':
828          return a.source == b.source &&
829                 a.global == b.global &&
830                 a.multiline == b.multiline &&
831                 a.ignoreCase == b.ignoreCase;
832      }
833      if (typeof a != 'object' || typeof b != 'object') return false;
834      // Assume equality for cyclic structures. The algorithm for detecting cyclic
835      // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
836      var length = aStack.length;
837      while (length--) {
838        // Linear search. Performance is inversely proportional to the number of
839        // unique nested structures.
840        if (aStack[length] == a) return bStack[length] == b;
841      }
842      // Add the first object to the stack of traversed objects.
843      aStack.push(a);
844      bStack.push(b);
845      var size = 0, result = true;
846      // Recursively compare objects and arrays.
847      if (className == '[object Array]') {
848        // Compare array lengths to determine if a deep comparison is necessary.
849        size = a.length;
850        result = size == b.length;
851        if (result) {
852          // Deep compare the contents, ignoring non-numeric properties.
853          while (size--) {
854            if (!(result = eq(a[size], b[size], aStack, bStack))) break;
855          }
856        }
857      } else {
858        // Objects with different constructors are not equivalent, but `Object`s
859        // from different frames are.
860        var aCtor = a.constructor, bCtor = b.constructor;
861        if (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor instanceof aCtor) &&
862                                 _.isFunction(bCtor) && (bCtor instanceof bCtor))) {
863          return false;
864        }
865        // Deep compare objects.
866        for (var key in a) {
867          if (_.has(a, key)) {
868            // Count the expected number of properties.
869            size++;
870            // Deep compare each member.
871            if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
872          }
873        }
874        // Ensure that both objects contain the same number of properties.
875        if (result) {
876          for (key in b) {
877            if (_.has(b, key) && !(size--)) break;
878          }
879          result = !size;
880        }
881      }
882      // Remove the first object from the stack of traversed objects.
883      aStack.pop();
884      bStack.pop();
885      return result;
886    };
887  
888    // Perform a deep comparison to check if two objects are equal.
889    _.isEqual = function(a, b) {
890      return eq(a, b, [], []);
891    };
892  
893    // Is a given array, string, or object empty?
894    // An "empty" object has no enumerable own-properties.
895    _.isEmpty = function(obj) {
896      if (obj == null) return true;
897      if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
898      for (var key in obj) if (_.has(obj, key)) return false;
899      return true;
900    };
901  
902    // Is a given value a DOM element?
903    _.isElement = function(obj) {
904      return !!(obj && obj.nodeType === 1);
905    };
906  
907    // Is a given value an array?
908    // Delegates to ECMA5's native Array.isArray
909    _.isArray = nativeIsArray || function(obj) {
910      return toString.call(obj) == '[object Array]';
911    };
912  
913    // Is a given variable an object?
914    _.isObject = function(obj) {
915      return obj === Object(obj);
916    };
917  
918    // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
919    each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
920      _['is' + name] = function(obj) {
921        return toString.call(obj) == '[object ' + name + ']';
922      };
923    });
924  
925    // Define a fallback version of the method in browsers (ahem, IE), where
926    // there isn't any inspectable "Arguments" type.
927    if (!_.isArguments(arguments)) {
928      _.isArguments = function(obj) {
929        return !!(obj && _.has(obj, 'callee'));
930      };
931    }
932  
933    // Optimize `isFunction` if appropriate.
934    if (typeof (/./) !== 'function') {
935      _.isFunction = function(obj) {
936        return typeof obj === 'function';
937      };
938    }
939  
940    // Is a given object a finite number?
941    _.isFinite = function(obj) {
942      return _.isNumber(obj) && isFinite(obj);
943    };
944  
945    // Is the given value `NaN`? (NaN is the only number which does not equal itself).
946    _.isNaN = function(obj) {
947      return _.isNumber(obj) && obj != +obj;
948    };
949  
950    // Is a given value a boolean?
951    _.isBoolean = function(obj) {
952      return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
953    };
954  
955    // Is a given value equal to null?
956    _.isNull = function(obj) {
957      return obj === null;
958    };
959  
960    // Is a given variable undefined?
961    _.isUndefined = function(obj) {
962      return obj === void 0;
963    };
964  
965    // Shortcut function for checking if an object has a given property directly
966    // on itself (in other words, not on a prototype).
967    _.has = function(obj, key) {
968      return hasOwnProperty.call(obj, key);
969    };
970  
971    // Utility Functions
972    // -----------------
973  
974    // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
975    // previous owner. Returns a reference to the Underscore object.
976    _.noConflict = function() {
977      root._ = previousUnderscore;
978      return this;
979    };
980  
981    // Keep the identity function around for default iterators.
982    _.identity = function(value) {
983      return value;
984    };
985  
986    // Run a function **n** times.
987    _.times = function(n, iterator, context) {
988      for (var i = 0; i < n; i++) iterator.call(context, i);
989    };
990  
991    // Return a random integer between min and max (inclusive).
992    _.random = function(min, max) {
993      if (max == null) {
994        max = min;
995        min = 0;
996      }
997      return min + (0 | Math.random() * (max - min + 1));
998    };
999  
1000    // List of HTML entities for escaping.
1001    var entityMap = {
1002      escape: {
1003        '&': '&amp;',
1004        '<': '<',
1005        '>': '>',
1006        '"': '&quot;',
1007        "'": '&#x27;',
1008        '/': '&#x2F;'
1009      }
1010    };
1011    entityMap.unescape = _.invert(entityMap.escape);
1012  
1013    // Regexes containing the keys and values listed immediately above.
1014    var entityRegexes = {
1015      escape:   new RegExp('[' + _.keys(entityMap.escape).join('') + ']', 'g'),
1016      unescape: new RegExp('(' + _.keys(entityMap.unescape).join('|') + ')', 'g')
1017    };
1018  
1019    // Functions for escaping and unescaping strings to/from HTML interpolation.
1020    _.each(['escape', 'unescape'], function(method) {
1021      _[method] = function(string) {
1022        if (string == null) return '';
1023        return ('' + string).replace(entityRegexes[method], function(match) {
1024          return entityMap[method][match];
1025        });
1026      };
1027    });
1028  
1029    // If the value of the named property is a function then invoke it;
1030    // otherwise, return it.
1031    _.result = function(object, property) {
1032      if (object == null) return null;
1033      var value = object[property];
1034      return _.isFunction(value) ? value.call(object) : value;
1035    };
1036  
1037    // Add your own custom functions to the Underscore object.
1038    _.mixin = function(obj) {
1039      each(_.functions(obj), function(name){
1040        var func = _[name] = obj[name];
1041        _.prototype[name] = function() {
1042          var args = [this._wrapped];
1043          push.apply(args, arguments);
1044          return result.call(this, func.apply(_, args));
1045        };
1046      });
1047    };
1048  
1049    // Generate a unique integer id (unique within the entire client session).
1050    // Useful for temporary DOM ids.
1051    var idCounter = 0;
1052    _.uniqueId = function(prefix) {
1053      var id = idCounter++;
1054      return prefix ? prefix + id : id;
1055    };
1056  
1057    // By default, Underscore uses ERB-style template delimiters, change the
1058    // following template settings to use alternative delimiters.
1059    _.templateSettings = {
1060      evaluate    : /<%([\s\S]+?)%>/g,
1061      interpolate : /<%=([\s\S]+?)%>/g,
1062      escape      : /<%-([\s\S]+?)%>/g
1063    };
1064  
1065    // When customizing `templateSettings`, if you don't want to define an
1066    // interpolation, evaluation or escaping regex, we need one that is
1067    // guaranteed not to match.
1068    var noMatch = /(.)^/;
1069  
1070    // Certain characters need to be escaped so that they can be put into a
1071    // string literal.
1072    var escapes = {
1073      "'":      "'",
1074      '\\':     '\\',
1075      '\r':     'r',
1076      '\n':     'n',
1077      '\t':     't',
1078      '\u2028': 'u2028',
1079      '\u2029': 'u2029'
1080    };
1081  
1082    var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
1083  
1084    // JavaScript micro-templating, similar to John Resig's implementation.
1085    // Underscore templating handles arbitrary delimiters, preserves whitespace,
1086    // and correctly escapes quotes within interpolated code.
1087    _.template = function(text, data, settings) {
1088      settings = _.defaults({}, settings, _.templateSettings);
1089  
1090      // Combine delimiters into one regular expression via alternation.
1091      var matcher = new RegExp([
1092        (settings.escape || noMatch).source,
1093        (settings.interpolate || noMatch).source,
1094        (settings.evaluate || noMatch).source
1095      ].join('|') + '|$', 'g');
1096  
1097      // Compile the template source, escaping string literals appropriately.
1098      var index = 0;
1099      var source = "__p+='";
1100      text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
1101        source += text.slice(index, offset)
1102          .replace(escaper, function(match) { return '\\' + escapes[match]; });
1103        source +=
1104          escape ? "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'" :
1105          interpolate ? "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'" :
1106          evaluate ? "';\n" + evaluate + "\n__p+='" : '';
1107        index = offset + match.length;
1108      });
1109      source += "';\n";
1110  
1111      // If a variable is not specified, place data values in local scope.
1112      if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
1113  
1114      source = "var __t,__p='',__j=Array.prototype.join," +
1115        "print=function(){__p+=__j.call(arguments,'');};\n" +
1116        source + "return __p;\n";
1117  
1118      try {
1119        var render = new Function(settings.variable || 'obj', '_', source);
1120      } catch (e) {
1121        e.source = source;
1122        throw e;
1123      }
1124  
1125      if (data) return render(data, _);
1126      var template = function(data) {
1127        return render.call(this, data, _);
1128      };
1129  
1130      // Provide the compiled function source as a convenience for precompilation.
1131      template.source = 'function(' + (settings.variable || 'obj') + '){\n' + source + '}';
1132  
1133      return template;
1134    };
1135  
1136    // Add a "chain" function, which will delegate to the wrapper.
1137    _.chain = function(obj) {
1138      return _(obj).chain();
1139    };
1140  
1141    // OOP
1142    // ---------------
1143    // If Underscore is called as a function, it returns a wrapped object that
1144    // can be used OO-style. This wrapper holds altered versions of all the
1145    // underscore functions. Wrapped objects may be chained.
1146  
1147    // Helper function to continue chaining intermediate results.
1148    var result = function(obj) {
1149      return this._chain ? _(obj).chain() : obj;
1150    };
1151  
1152    // Add all of the Underscore functions to the wrapper object.
1153    _.mixin(_);
1154  
1155    // Add all mutator Array functions to the wrapper.
1156    each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
1157      var method = ArrayProto[name];
1158      _.prototype[name] = function() {
1159        var obj = this._wrapped;
1160        method.apply(obj, arguments);
1161        if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
1162        return result.call(this, obj);
1163      };
1164    });
1165  
1166    // Add all accessor Array functions to the wrapper.
1167    each(['concat', 'join', 'slice'], function(name) {
1168      var method = ArrayProto[name];
1169      _.prototype[name] = function() {
1170        return result.call(this, method.apply(this._wrapped, arguments));
1171      };
1172    });
1173  
1174    _.extend(_.prototype, {
1175  
1176      // Start chaining a wrapped Underscore object.
1177      chain: function() {
1178        this._chain = true;
1179        return this;
1180      },
1181  
1182      // Extracts the result from a wrapped and chained object.
1183      value: function() {
1184        return this._wrapped;
1185      }
1186  
1187    });
1188  
1189  }).call(this);
//     Underscore.js 1.4.1
2	//     http://underscorejs.org
3	//     (c) 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.
4	//     Underscore may be freely distributed under the MIT license.
5	
6	(function() {
7	
8	  // Baseline setup
9	  // --------------
10	
11	  // Establish the root object, `window` in the browser, or `global` on the server.
12	  var root = this;
13	
14	  // Save the previous value of the `_` variable.
15	  var previousUnderscore = root._;
16	
17	  // Establish the object that gets returned to break out of a loop iteration.
18	  var breaker = {};
19	
20	  // Save bytes in the minified (but not gzipped) version:
21	  var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
22	
23	  // Create quick reference variables for speed access to core prototypes.
24	  var push             = ArrayProto.push,
25	      slice            = ArrayProto.slice,
26	      concat           = ArrayProto.concat,
27	      unshift          = ArrayProto.unshift,
28	      toString         = ObjProto.toString,
29	      hasOwnProperty   = ObjProto.hasOwnProperty;
30	
31	  // All **ECMAScript 5** native function implementations that we hope to use
32	  // are declared here.
33	  var
34	    nativeForEach      = ArrayProto.forEach,
35	    nativeMap          = ArrayProto.map,
36	    nativeReduce       = ArrayProto.reduce,
37	    nativeReduceRight  = ArrayProto.reduceRight,
38	    nativeFilter       = ArrayProto.filter,
39	    nativeEvery        = ArrayProto.every,
40	    nativeSome         = ArrayProto.some,
41	    nativeIndexOf      = ArrayProto.indexOf,
42	    nativeLastIndexOf  = ArrayProto.lastIndexOf,
43	    nativeIsArray      = Array.isArray,
44	    nativeKeys         = Object.keys,
45	    nativeBind         = FuncProto.bind;
46	
47	  // Create a safe reference to the Underscore object for use below.
48	  var _ = function(obj) {
49	    if (obj instanceof _) return obj;
50	    if (!(this instanceof _)) return new _(obj);
51	    this._wrapped = obj;
52	  };
53	
54	  // Export the Underscore object for **Node.js**, with
55	  // backwards-compatibility for the old `require()` API. If we're in
56	  // the browser, add `_` as a global object via a string identifier,
57	  // for Closure Compiler "advanced" mode.
58	  if (typeof exports !== 'undefined') {
59	    if (typeof module !== 'undefined' && module.exports) {
60	      exports = module.exports = _;
61	    }
62	    exports._ = _;
63	  } else {
64	    root['_'] = _;
65	  }
66	
67	  // Current version.
68	  _.VERSION = '1.4.1';
69	
70	  // Collection Functions
71	  // --------------------
72	
73	  // The cornerstone, an `each` implementation, aka `forEach`.
74	  // Handles objects with the built-in `forEach`, arrays, and raw objects.
75	  // Delegates to **ECMAScript 5**'s native `forEach` if available.
76	  var each = _.each = _.forEach = function(obj, iterator, context) {
77	    if (nativeForEach && obj.forEach === nativeForEach) {
78	      obj.forEach(iterator, context);
79	    } else if (obj.length === +obj.length) {
80	      for (var i = 0, l = obj.length; i < l; i++) {
81	        if (iterator.call(context, obj[i], i, obj) === breaker) return;
82	      }
83	    } else {
84	      for (var key in obj) {
85	        if (_.has(obj, key)) {
86	          if (iterator.call(context, obj[key], key, obj) === breaker) return;
87	        }
88	      }
89	    }
90	  };
91	
92	  // Return the results of applying the iterator to each element.
93	  // Delegates to **ECMAScript 5**'s native `map` if available.
94	  _.map = _.collect = function(obj, iterator, context) {
95	    var results = [];
96	    if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
97	    each(obj, function(value, index, list) {
98	      results[results.length] = iterator.call(context, value, index, list);
99	    });
100	    return results;
101	  };
102	
103	  // **Reduce** builds up a single result from a list of values, aka `inject`,
104	  // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
105	  _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
106	    var initial = arguments.length > 2;
107	    if (nativeReduce && obj.reduce === nativeReduce) {
108	      if (context) iterator = _.bind(iterator, context);
109	      return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
110	    }
111	    each(obj, function(value, index, list) {
112	      if (!initial) {
113	        memo = value;
114	        initial = true;
115	      } else {
116	        memo = iterator.call(context, memo, value, index, list);
117	      }
118	    });
119	    if (!initial) throw new TypeError('Reduce of empty array with no initial value');
120	    return memo;
121	  };
122	
123	  // The right-associative version of reduce, also known as `foldr`.
124	  // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
125	  _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
126	    var initial = arguments.length > 2;
127	    if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
128	      if (context) iterator = _.bind(iterator, context);
129	      return arguments.length > 2 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
130	    }
131	    var length = obj.length;
132	    if (length !== +length) {
133	      var keys = _.keys(obj);
134	      length = keys.length;
135	    }
136	    each(obj, function(value, index, list) {
137	      index = keys ? keys[--length] : --length;
138	      if (!initial) {
139	        memo = obj[index];
140	        initial = true;
141	      } else {
142	        memo = iterator.call(context, memo, obj[index], index, list);
143	      }
144	    });
145	    if (!initial) throw new TypeError('Reduce of empty array with no initial value');
146	    return memo;
147	  };
148	
149	  // Return the first value which passes a truth test. Aliased as `detect`.
150	  _.find = _.detect = function(obj, iterator, context) {
151	    var result;
152	    any(obj, function(value, index, list) {
153	      if (iterator.call(context, value, index, list)) {
154	        result = value;
155	        return true;
156	      }
157	    });
158	    return result;
159	  };
160	
161	  // Return all the elements that pass a truth test.
162	  // Delegates to **ECMAScript 5**'s native `filter` if available.
163	  // Aliased as `select`.
164	  _.filter = _.select = function(obj, iterator, context) {
165	    var results = [];
166	    if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
167	    each(obj, function(value, index, list) {
168	      if (iterator.call(context, value, index, list)) results[results.length] = value;
169	    });
170	    return results;
171	  };
172	
173	  // Return all the elements for which a truth test fails.
174	  _.reject = function(obj, iterator, context) {
175	    var results = [];
176	    each(obj, function(value, index, list) {
177	      if (!iterator.call(context, value, index, list)) results[results.length] = value;
178	    });
179	    return results;
180	  };
181	
182	  // Determine whether all of the elements match a truth test.
183	  // Delegates to **ECMAScript 5**'s native `every` if available.
184	  // Aliased as `all`.
185	  _.every = _.all = function(obj, iterator, context) {
186	    iterator || (iterator = _.identity);
187	    var result = true;
188	    if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
189	    each(obj, function(value, index, list) {
190	      if (!(result = result && iterator.call(context, value, index, list))) return breaker;
191	    });
192	    return !!result;
193	  };
194	
195	  // Determine if at least one element in the object matches a truth test.
196	  // Delegates to **ECMAScript 5**'s native `some` if available.
197	  // Aliased as `any`.
198	  var any = _.some = _.any = function(obj, iterator, context) {
199	    iterator || (iterator = _.identity);
200	    var result = false;
201	    if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
202	    each(obj, function(value, index, list) {
203	      if (result || (result = iterator.call(context, value, index, list))) return breaker;
204	    });
205	    return !!result;
206	  };
207	
208	  // Determine if the array or object contains a given value (using `===`).
209	  // Aliased as `include`.
210	  _.contains = _.include = function(obj, target) {
211	    var found = false;
212	    if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
213	    found = any(obj, function(value) {
214	      return value === target;
215	    });
216	    return found;
217	  };
218	
219	  // Invoke a method (with arguments) on every item in a collection.
220	  _.invoke = function(obj, method) {
221	    var args = slice.call(arguments, 2);
222	    return _.map(obj, function(value) {
223	      return (_.isFunction(method) ? method : value[method]).apply(value, args);
224	    });
225	  };
226	
227	  // Convenience version of a common use case of `map`: fetching a property.
228	  _.pluck = function(obj, key) {
229	    return _.map(obj, function(value){ return value[key]; });
230	  };
231	
232	  // Convenience version of a common use case of `filter`: selecting only objects
233	  // with specific `key:value` pairs.
234	  _.where = function(obj, attrs) {
235	    if (_.isEmpty(attrs)) return [];
236	    return _.filter(obj, function(value) {
237	      for (var key in attrs) {
238	        if (attrs[key] !== value[key]) return false;
239	      }
240	      return true;
241	    });
242	  };
243	
244	  // Return the maximum element or (element-based computation).
245	  // Can't optimize arrays of integers longer than 65,535 elements.
246	  // See: https://bugs.webkit.org/show_bug.cgi?id=80797
247	  _.max = function(obj, iterator, context) {
248	    if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
249	      return Math.max.apply(Math, obj);
250	    }
251	    if (!iterator && _.isEmpty(obj)) return -Infinity;
252	    var result = {computed : -Infinity};
253	    each(obj, function(value, index, list) {
254	      var computed = iterator ? iterator.call(context, value, index, list) : value;
255	      computed >= result.computed && (result = {value : value, computed : computed});
256	    });
257	    return result.value;
258	  };
259	
260	  // Return the minimum element (or element-based computation).
261	  _.min = function(obj, iterator, context) {
262	    if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
263	      return Math.min.apply(Math, obj);
264	    }
265	    if (!iterator && _.isEmpty(obj)) return Infinity;
266	    var result = {computed : Infinity};
267	    each(obj, function(value, index, list) {
268	      var computed = iterator ? iterator.call(context, value, index, list) : value;
269	      computed < result.computed && (result = {value : value, computed : computed});
270	    });
271	    return result.value;
272	  };
273	
274	  // Shuffle an array.
275	  _.shuffle = function(obj) {
276	    var rand;
277	    var index = 0;
278	    var shuffled = [];
279	    each(obj, function(value) {
280	      rand = _.random(index++);
281	      shuffled[index - 1] = shuffled[rand];
282	      shuffled[rand] = value;
283	    });
284	    return shuffled;
285	  };
286	
287	  // An internal function to generate lookup iterators.
288	  var lookupIterator = function(value) {
289	    return _.isFunction(value) ? value : function(obj){ return obj[value]; };
290	  };
291	
292	  // Sort the object's values by a criterion produced by an iterator.
293	  _.sortBy = function(obj, value, context) {
294	    var iterator = lookupIterator(value);
295	    return _.pluck(_.map(obj, function(value, index, list) {
296	      return {
297	        value : value,
298	        index : index,
299	        criteria : iterator.call(context, value, index, list)
300	      };
301	    }).sort(function(left, right) {
302	      var a = left.criteria;
303	      var b = right.criteria;
304	      if (a !== b) {
305	        if (a > b || a === void 0) return 1;
306	        if (a < b || b === void 0) return -1;
307	      }
308	      return left.index < right.index ? -1 : 1;
309	    }), 'value');
310	  };
311	
312	  // An internal function used for aggregate "group by" operations.
313	  var group = function(obj, value, context, behavior) {
314	    var result = {};
315	    var iterator = lookupIterator(value);
316	    each(obj, function(value, index) {
317	      var key = iterator.call(context, value, index, obj);
318	      behavior(result, key, value);
319	    });
320	    return result;
321	  };
322	
323	  // Groups the object's values by a criterion. Pass either a string attribute
324	  // to group by, or a function that returns the criterion.
325	  _.groupBy = function(obj, value, context) {
326	    return group(obj, value, context, function(result, key, value) {
327	      (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
328	    });
329	  };
330	
331	  // Counts instances of an object that group by a certain criterion. Pass
332	  // either a string attribute to count by, or a function that returns the
333	  // criterion.
334	  _.countBy = function(obj, value, context) {
335	    return group(obj, value, context, function(result, key, value) {
336	      if (!_.has(result, key)) result[key] = 0;
337	      result[key]++;
338	    });
339	  };
340	
341	  // Use a comparator function to figure out the smallest index at which
342	  // an object should be inserted so as to maintain order. Uses binary search.
343	  _.sortedIndex = function(array, obj, iterator, context) {
344	    iterator = iterator == null ? _.identity : lookupIterator(iterator);
345	    var value = iterator.call(context, obj);
346	    var low = 0, high = array.length;
347	    while (low < high) {
348	      var mid = (low + high) >>> 1;
349	      iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
350	    }
351	    return low;
352	  };
353	
354	  // Safely convert anything iterable into a real, live array.
355	  _.toArray = function(obj) {
356	    if (!obj) return [];
357	    if (obj.length === +obj.length) return slice.call(obj);
358	    return _.values(obj);
359	  };
360	
361	  // Return the number of elements in an object.
362	  _.size = function(obj) {
363	    return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
364	  };
365	
366	  // Array Functions
367	  // ---------------
368	
369	  // Get the first element of an array. Passing **n** will return the first N
370	  // values in the array. Aliased as `head` and `take`. The **guard** check
371	  // allows it to work with `_.map`.
372	  _.first = _.head = _.take = function(array, n, guard) {
373	    return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
374	  };
375	
376	  // Returns everything but the last entry of the array. Especially useful on
377	  // the arguments object. Passing **n** will return all the values in
378	  // the array, excluding the last N. The **guard** check allows it to work with
379	  // `_.map`.
380	  _.initial = function(array, n, guard) {
381	    return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
382	  };
383	
384	  // Get the last element of an array. Passing **n** will return the last N
385	  // values in the array. The **guard** check allows it to work with `_.map`.
386	  _.last = function(array, n, guard) {
387	    if ((n != null) && !guard) {
388	      return slice.call(array, Math.max(array.length - n, 0));
389	    } else {
390	      return array[array.length - 1];
391	    }
392	  };
393	
394	  // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
395	  // Especially useful on the arguments object. Passing an **n** will return
396	  // the rest N values in the array. The **guard**
397	  // check allows it to work with `_.map`.
398	  _.rest = _.tail = _.drop = function(array, n, guard) {
399	    return slice.call(array, (n == null) || guard ? 1 : n);
400	  };
401	
402	  // Trim out all falsy values from an array.
403	  _.compact = function(array) {
404	    return _.filter(array, function(value){ return !!value; });
405	  };
406	
407	  // Internal implementation of a recursive `flatten` function.
408	  var flatten = function(input, shallow, output) {
409	    each(input, function(value) {
410	      if (_.isArray(value)) {
411	        shallow ? push.apply(output, value) : flatten(value, shallow, output);
412	      } else {
413	        output.push(value);
414	      }
415	    });
416	    return output;
417	  };
418	
419	  // Return a completely flattened version of an array.
420	  _.flatten = function(array, shallow) {
421	    return flatten(array, shallow, []);
422	  };
423	
424	  // Return a version of the array that does not contain the specified value(s).
425	  _.without = function(array) {
426	    return _.difference(array, slice.call(arguments, 1));
427	  };
428	
429	  // Produce a duplicate-free version of the array. If the array has already
430	  // been sorted, you have the option of using a faster algorithm.
431	  // Aliased as `unique`.
432	  _.uniq = _.unique = function(array, isSorted, iterator, context) {
433	    var initial = iterator ? _.map(array, iterator, context) : array;
434	    var results = [];
435	    var seen = [];
436	    each(initial, function(value, index) {
437	      if (isSorted ? (!index || seen[seen.length - 1] !== value) : !_.contains(seen, value)) {
438	        seen.push(value);
439	        results.push(array[index]);
440	      }
441	    });
442	    return results;
443	  };
444	
445	  // Produce an array that contains the union: each distinct element from all of
446	  // the passed-in arrays.
447	  _.union = function() {
448	    return _.uniq(concat.apply(ArrayProto, arguments));
449	  };
450	
451	  // Produce an array that contains every item shared between all the
452	  // passed-in arrays.
453	  _.intersection = function(array) {
454	    var rest = slice.call(arguments, 1);
455	    return _.filter(_.uniq(array), function(item) {
456	      return _.every(rest, function(other) {
457	        return _.indexOf(other, item) >= 0;
458	      });
459	    });
460	  };
461	
462	  // Take the difference between one array and a number of other arrays.
463	  // Only the elements present in just the first array will remain.
464	  _.difference = function(array) {
465	    var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
466	    return _.filter(array, function(value){ return !_.contains(rest, value); });
467	  };
468	
469	  // Zip together multiple lists into a single array -- elements that share
470	  // an index go together.
471	  _.zip = function() {
472	    var args = slice.call(arguments);
473	    var length = _.max(_.pluck(args, 'length'));
474	    var results = new Array(length);
475	    for (var i = 0; i < length; i++) {
476	      results[i] = _.pluck(args, "" + i);
477	    }
478	    return results;
479	  };
480	
481	  // Converts lists into objects. Pass either a single array of `[key, value]`
482	  // pairs, or two parallel arrays of the same length -- one of keys, and one of
483	  // the corresponding values.
484	  _.object = function(list, values) {
485	    var result = {};
486	    for (var i = 0, l = list.length; i < l; i++) {
487	      if (values) {
488	        result[list[i]] = values[i];
489	      } else {
490	        result[list[i][0]] = list[i][1];
491	      }
492	    }
493	    return result;
494	  };
495	
496	  // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
497	  // we need this function. Return the position of the first occurrence of an
498	  // item in an array, or -1 if the item is not included in the array.
499	  // Delegates to **ECMAScript 5**'s native `indexOf` if available.
500	  // If the array is large and already in sort order, pass `true`
501	  // for **isSorted** to use binary search.
502	  _.indexOf = function(array, item, isSorted) {
503	    var i = 0, l = array.length;
504	    if (isSorted) {
505	      if (typeof isSorted == 'number') {
506	        i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
507	      } else {
508	        i = _.sortedIndex(array, item);
509	        return array[i] === item ? i : -1;
510	      }
511	    }
512	    if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
513	    for (; i < l; i++) if (array[i] === item) return i;
514	    return -1;
515	  };
516	
517	  // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
518	  _.lastIndexOf = function(array, item, from) {
519	    var hasIndex = from != null;
520	    if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
521	      return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
522	    }
523	    var i = (hasIndex ? from : array.length);
524	    while (i--) if (array[i] === item) return i;
525	    return -1;
526	  };
527	
528	  // Generate an integer Array containing an arithmetic progression. A port of
529	  // the native Python `range()` function. See
530	  // [the Python documentation](http://docs.python.org/library/functions.html#range).
531	  _.range = function(start, stop, step) {
532	    if (arguments.length <= 1) {
533	      stop = start || 0;
534	      start = 0;
535	    }
536	    step = arguments[2] || 1;
537	
538	    var len = Math.max(Math.ceil((stop - start) / step), 0);
539	    var idx = 0;
540	    var range = new Array(len);
541	
542	    while(idx < len) {
543	      range[idx++] = start;
544	      start += step;
545	    }
546	
547	    return range;
548	  };
549	
550	  // Function (ahem) Functions
551	  // ------------------
552	
553	  // Reusable constructor function for prototype setting.
554	  var ctor = function(){};
555	
556	  // Create a function bound to a given object (assigning `this`, and arguments,
557	  // optionally). Binding with arguments is also known as `curry`.
558	  // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
559	  // We check for `func.bind` first, to fail fast when `func` is undefined.
560	  _.bind = function bind(func, context) {
561	    var bound, args;
562	    if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
563	    if (!_.isFunction(func)) throw new TypeError;
564	    args = slice.call(arguments, 2);
565	    return bound = function() {
566	      if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
567	      ctor.prototype = func.prototype;
568	      var self = new ctor;
569	      var result = func.apply(self, args.concat(slice.call(arguments)));
570	      if (Object(result) === result) return result;
571	      return self;
572	    };
573	  };
574	
575	  // Bind all of an object's methods to that object. Useful for ensuring that
576	  // all callbacks defined on an object belong to it.
577	  _.bindAll = function(obj) {
578	    var funcs = slice.call(arguments, 1);
579	    if (funcs.length == 0) funcs = _.functions(obj);
580	    each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
581	    return obj;
582	  };
583	
584	  // Memoize an expensive function by storing its results.
585	  _.memoize = function(func, hasher) {
586	    var memo = {};
587	    hasher || (hasher = _.identity);
588	    return function() {
589	      var key = hasher.apply(this, arguments);
590	      return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
591	    };
592	  };
593	
594	  // Delays a function for the given number of milliseconds, and then calls
595	  // it with the arguments supplied.
596	  _.delay = function(func, wait) {
597	    var args = slice.call(arguments, 2);
598	    return setTimeout(function(){ return func.apply(null, args); }, wait);
599	  };
600	
601	  // Defers a function, scheduling it to run after the current call stack has
602	  // cleared.
603	  _.defer = function(func) {
604	    return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
605	  };
606	
607	  // Returns a function, that, when invoked, will only be triggered at most once
608	  // during a given window of time.
609	  _.throttle = function(func, wait) {
610	    var context, args, timeout, throttling, more, result;
611	    var whenDone = _.debounce(function(){ more = throttling = false; }, wait);
612	    return function() {
613	      context = this; args = arguments;
614	      var later = function() {
615	        timeout = null;
616	        if (more) {
617	          result = func.apply(context, args);
618	        }
619	        whenDone();
620	      };
621	      if (!timeout) timeout = setTimeout(later, wait);
622	      if (throttling) {
623	        more = true;
624	      } else {
625	        throttling = true;
626	        result = func.apply(context, args);
627	      }
628	      whenDone();
629	      return result;
630	    };
631	  };
632	
633	  // Returns a function, that, as long as it continues to be invoked, will not
634	  // be triggered. The function will be called after it stops being called for
635	  // N milliseconds. If `immediate` is passed, trigger the function on the
636	  // leading edge, instead of the trailing.
637	  _.debounce = function(func, wait, immediate) {
638	    var timeout, result;
639	    return function() {
640	      var context = this, args = arguments;
641	      var later = function() {
642	        timeout = null;
643	        if (!immediate) result = func.apply(context, args);
644	      };
645	      var callNow = immediate && !timeout;
646	      clearTimeout(timeout);
647	      timeout = setTimeout(later, wait);
648	      if (callNow) result = func.apply(context, args);
649	      return result;
650	    };
651	  };
652	
653	  // Returns a function that will be executed at most one time, no matter how
654	  // often you call it. Useful for lazy initialization.
655	  _.once = function(func) {
656	    var ran = false, memo;
657	    return function() {
658	      if (ran) return memo;
659	      ran = true;
660	      memo = func.apply(this, arguments);
661	      func = null;
662	      return memo;
663	    };
664	  };
665	
666	  // Returns the first function passed as an argument to the second,
667	  // allowing you to adjust arguments, run code before and after, and
668	  // conditionally execute the original function.
669	  _.wrap = function(func, wrapper) {
670	    return function() {
671	      var args = [func];
672	      push.apply(args, arguments);
673	      return wrapper.apply(this, args);
674	    };
675	  };
676	
677	  // Returns a function that is the composition of a list of functions, each
678	  // consuming the return value of the function that follows.
679	  _.compose = function() {
680	    var funcs = arguments;
681	    return function() {
682	      var args = arguments;
683	      for (var i = funcs.length - 1; i >= 0; i--) {
684	        args = [funcs[i].apply(this, args)];
685	      }
686	      return args[0];
687	    };
688	  };
689	
690	  // Returns a function that will only be executed after being called N times.
691	  _.after = function(times, func) {
692	    if (times <= 0) return func();
693	    return function() {
694	      if (--times < 1) {
695	        return func.apply(this, arguments);
696	      }
697	    };
698	  };
699	
700	  // Object Functions
701	  // ----------------
702	
703	  // Retrieve the names of an object's properties.
704	  // Delegates to **ECMAScript 5**'s native `Object.keys`
705	  _.keys = nativeKeys || function(obj) {
706	    if (obj !== Object(obj)) throw new TypeError('Invalid object');
707	    var keys = [];
708	    for (var key in obj) if (_.has(obj, key)) keys[keys.length] = key;
709	    return keys;
710	  };
711	
712	  // Retrieve the values of an object's properties.
713	  _.values = function(obj) {
714	    var values = [];
715	    for (var key in obj) if (_.has(obj, key)) values.push(obj[key]);
716	    return values;
717	  };
718	
719	  // Convert an object into a list of `[key, value]` pairs.
720	  _.pairs = function(obj) {
721	    var pairs = [];
722	    for (var key in obj) if (_.has(obj, key)) pairs.push([key, obj[key]]);
723	    return pairs;
724	  };
725	
726	  // Invert the keys and values of an object. The values must be serializable.
727	  _.invert = function(obj) {
728	    var result = {};
729	    for (var key in obj) if (_.has(obj, key)) result[obj[key]] = key;
730	    return result;
731	  };
732	
733	  // Return a sorted list of the function names available on the object.
734	  // Aliased as `methods`
735	  _.functions = _.methods = function(obj) {
736	    var names = [];
737	    for (var key in obj) {
738	      if (_.isFunction(obj[key])) names.push(key);
739	    }
740	    return names.sort();
741	  };
742	
743	  // Extend a given object with all the properties in passed-in object(s).
744	  _.extend = function(obj) {
745	    each(slice.call(arguments, 1), function(source) {
746	      for (var prop in source) {
747	        obj[prop] = source[prop];
748	      }
749	    });
750	    return obj;
751	  };
752	
753	  // Return a copy of the object only containing the whitelisted properties.
754	  _.pick = function(obj) {
755	    var copy = {};
756	    var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
757	    each(keys, function(key) {
758	      if (key in obj) copy[key] = obj[key];
759	    });
760	    return copy;
761	  };
762	
763	   // Return a copy of the object without the blacklisted properties.
764	  _.omit = function(obj) {
765	    var copy = {};
766	    var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
767	    for (var key in obj) {
768	      if (!_.contains(keys, key)) copy[key] = obj[key];
769	    }
770	    return copy;
771	  };
772	
773	  // Fill in a given object with default properties.
774	  _.defaults = function(obj) {
775	    each(slice.call(arguments, 1), function(source) {
776	      for (var prop in source) {
777	        if (obj[prop] == null) obj[prop] = source[prop];
778	      }
779	    });
780	    return obj;
781	  };
782	
783	  // Create a (shallow-cloned) duplicate of an object.
784	  _.clone = function(obj) {
785	    if (!_.isObject(obj)) return obj;
786	    return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
787	  };
788	
789	  // Invokes interceptor with the obj, and then returns obj.
790	  // The primary purpose of this method is to "tap into" a method chain, in
791	  // order to perform operations on intermediate results within the chain.
792	  _.tap = function(obj, interceptor) {
793	    interceptor(obj);
794	    return obj;
795	  };
796	
797	  // Internal recursive comparison function for `isEqual`.
798	  var eq = function(a, b, aStack, bStack) {
799	    // Identical objects are equal. `0 === -0`, but they aren't identical.
800	    // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.
801	    if (a === b) return a !== 0 || 1 / a == 1 / b;
802	    // A strict comparison is necessary because `null == undefined`.
803	    if (a == null || b == null) return a === b;
804	    // Unwrap any wrapped objects.
805	    if (a instanceof _) a = a._wrapped;
806	    if (b instanceof _) b = b._wrapped;
807	    // Compare `[[Class]]` names.
808	    var className = toString.call(a);
809	    if (className != toString.call(b)) return false;
810	    switch (className) {
811	      // Strings, numbers, dates, and booleans are compared by value.
812	      case '[object String]':
813	        // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
814	        // equivalent to `new String("5")`.
815	        return a == String(b);
816	      case '[object Number]':
817	        // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
818	        // other numeric values.
819	        return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
820	      case '[object Date]':
821	      case '[object Boolean]':
822	        // Coerce dates and booleans to numeric primitive values. Dates are compared by their
823	        // millisecond representations. Note that invalid dates with millisecond representations
824	        // of `NaN` are not equivalent.
825	        return +a == +b;
826	      // RegExps are compared by their source patterns and flags.
827	      case '[object RegExp]':
828	        return a.source == b.source &&
829	               a.global == b.global &&
830	               a.multiline == b.multiline &&
831	               a.ignoreCase == b.ignoreCase;
832	    }
833	    if (typeof a != 'object' || typeof b != 'object') return false;
834	    // Assume equality for cyclic structures. The algorithm for detecting cyclic
835	    // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
836	    var length = aStack.length;
837	    while (length--) {
838	      // Linear search. Performance is inversely proportional to the number of
839	      // unique nested structures.
840	      if (aStack[length] == a) return bStack[length] == b;
841	    }
842	    // Add the first object to the stack of traversed objects.
843	    aStack.push(a);
844	    bStack.push(b);
845	    var size = 0, result = true;
846	    // Recursively compare objects and arrays.
847	    if (className == '[object Array]') {
848	      // Compare array lengths to determine if a deep comparison is necessary.
849	      size = a.length;
850	      result = size == b.length;
851	      if (result) {
852	        // Deep compare the contents, ignoring non-numeric properties.
853	        while (size--) {
854	          if (!(result = eq(a[size], b[size], aStack, bStack))) break;
855	        }
856	      }
857	    } else {
858	      // Objects with different constructors are not equivalent, but `Object`s
859	      // from different frames are.
860	      var aCtor = a.constructor, bCtor = b.constructor;
861	      if (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor instanceof aCtor) &&
862	                               _.isFunction(bCtor) && (bCtor instanceof bCtor))) {
863	        return false;
864	      }
865	      // Deep compare objects.
866	      for (var key in a) {
867	        if (_.has(a, key)) {
868	          // Count the expected number of properties.
869	          size++;
870	          // Deep compare each member.
871	          if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
872	        }
873	      }
874	      // Ensure that both objects contain the same number of properties.
875	      if (result) {
876	        for (key in b) {
877	          if (_.has(b, key) && !(size--)) break;
878	        }
879	        result = !size;
880	      }
881	    }
882	    // Remove the first object from the stack of traversed objects.
883	    aStack.pop();
884	    bStack.pop();
885	    return result;
886	  };
887	
888	  // Perform a deep comparison to check if two objects are equal.
889	  _.isEqual = function(a, b) {
890	    return eq(a, b, [], []);
891	  };
892	
893	  // Is a given array, string, or object empty?
894	  // An "empty" object has no enumerable own-properties.
895	  _.isEmpty = function(obj) {
896	    if (obj == null) return true;
897	    if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
898	    for (var key in obj) if (_.has(obj, key)) return false;
899	    return true;
900	  };
901	
902	  // Is a given value a DOM element?
903	  _.isElement = function(obj) {
904	    return !!(obj && obj.nodeType === 1);
905	  };
906	
907	  // Is a given value an array?
908	  // Delegates to ECMA5's native Array.isArray
909	  _.isArray = nativeIsArray || function(obj) {
910	    return toString.call(obj) == '[object Array]';
911	  };
912	
913	  // Is a given variable an object?
914	  _.isObject = function(obj) {
915	    return obj === Object(obj);
916	  };
917	
918	  // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
919	  each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
920	    _['is' + name] = function(obj) {
921	      return toString.call(obj) == '[object ' + name + ']';
922	    };
923	  });
924	
925	  // Define a fallback version of the method in browsers (ahem, IE), where
926	  // there isn't any inspectable "Arguments" type.
927	  if (!_.isArguments(arguments)) {
928	    _.isArguments = function(obj) {
929	      return !!(obj && _.has(obj, 'callee'));
930	    };
931	  }
932	
933	  // Optimize `isFunction` if appropriate.
934	  if (typeof (/./) !== 'function') {
935	    _.isFunction = function(obj) {
936	      return typeof obj === 'function';
937	    };
938	  }
939	
940	  // Is a given object a finite number?
941	  _.isFinite = function(obj) {
942	    return _.isNumber(obj) && isFinite(obj);
943	  };
944	
945	  // Is the given value `NaN`? (NaN is the only number which does not equal itself).
946	  _.isNaN = function(obj) {
947	    return _.isNumber(obj) && obj != +obj;
948	  };
949	
950	  // Is a given value a boolean?
951	  _.isBoolean = function(obj) {
952	    return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
953	  };
954	
955	  // Is a given value equal to null?
956	  _.isNull = function(obj) {
957	    return obj === null;
958	  };
959	
960	  // Is a given variable undefined?
961	  _.isUndefined = function(obj) {
962	    return obj === void 0;
963	  };
964	
965	  // Shortcut function for checking if an object has a given property directly
966	  // on itself (in other words, not on a prototype).
967	  _.has = function(obj, key) {
968	    return hasOwnProperty.call(obj, key);
969	  };
970	
971	  // Utility Functions
972	  // -----------------
973	
974	  // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
975	  // previous owner. Returns a reference to the Underscore object.
976	  _.noConflict = function() {
977	    root._ = previousUnderscore;
978	    return this;
979	  };
980	
981	  // Keep the identity function around for default iterators.
982	  _.identity = function(value) {
983	    return value;
984	  };
985	
986	  // Run a function **n** times.
987	  _.times = function(n, iterator, context) {
988	    for (var i = 0; i < n; i++) iterator.call(context, i);
989	  };
990	
991	  // Return a random integer between min and max (inclusive).
992	  _.random = function(min, max) {
993	    if (max == null) {
994	      max = min;
995	      min = 0;
996	    }
997	    return min + (0 | Math.random() * (max - min + 1));
998	  };
999	
1000	  // List of HTML entities for escaping.
1001	  var entityMap = {
1002	    escape: {
1003	      '&': '&amp;',
1004	      '<': '&lt;',
1005	      '>': '&gt;',
1006	      '"': '&quot;',
1007	      "'": '&#x27;',
1008	      '/': '&#x2F;'
1009	    }
1010	  };
1011	  entityMap.unescape = _.invert(entityMap.escape);
1012	
1013	  // Regexes containing the keys and values listed immediately above.
1014	  var entityRegexes = {
1015	    escape:   new RegExp('[' + _.keys(entityMap.escape).join('') + ']', 'g'),
1016	    unescape: new RegExp('(' + _.keys(entityMap.unescape).join('|') + ')', 'g')
1017	  };
1018	
1019	  // Functions for escaping and unescaping strings to/from HTML interpolation.
1020	  _.each(['escape', 'unescape'], function(method) {
1021	    _[method] = function(string) {
1022	      if (string == null) return '';
1023	      return ('' + string).replace(entityRegexes[method], function(match) {
1024	        return entityMap[method][match];
1025	      });
1026	    };
1027	  });
1028	
1029	  // If the value of the named property is a function then invoke it;
1030	  // otherwise, return it.
1031	  _.result = function(object, property) {
1032	    if (object == null) return null;
1033	    var value = object[property];
1034	    return _.isFunction(value) ? value.call(object) : value;
1035	  };
1036	
1037	  // Add your own custom functions to the Underscore object.
1038	  _.mixin = function(obj) {
1039	    each(_.functions(obj), function(name){
1040	      var func = _[name] = obj[name];
1041	      _.prototype[name] = function() {
1042	        var args = [this._wrapped];
1043	        push.apply(args, arguments);
1044	        return result.call(this, func.apply(_, args));
1045	      };
1046	    });
1047	  };
1048	
1049	  // Generate a unique integer id (unique within the entire client session).
1050	  // Useful for temporary DOM ids.
1051	  var idCounter = 0;
1052	  _.uniqueId = function(prefix) {
1053	    var id = idCounter++;
1054	    return prefix ? prefix + id : id;
1055	  };
1056	
1057	  // By default, Underscore uses ERB-style template delimiters, change the
1058	  // following template settings to use alternative delimiters.
1059	  _.templateSettings = {
1060	    evaluate    : /<%([\s\S]+?)%>/g,
1061	    interpolate : /<%=([\s\S]+?)%>/g,
1062	    escape      : /<%-([\s\S]+?)%>/g
1063	  };
1064	
1065	  // When customizing `templateSettings`, if you don't want to define an
1066	  // interpolation, evaluation or escaping regex, we need one that is
1067	  // guaranteed not to match.
1068	  var noMatch = /(.)^/;
1069	
1070	  // Certain characters need to be escaped so that they can be put into a
1071	  // string literal.
1072	  var escapes = {
1073	    "'":      "'",
1074	    '\\':     '\\',
1075	    '\r':     'r',
1076	    '\n':     'n',
1077	    '\t':     't',
1078	    '\u2028': 'u2028',
1079	    '\u2029': 'u2029'
1080	  };
1081	
1082	  var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
1083	
1084	  // JavaScript micro-templating, similar to John Resig's implementation.
1085	  // Underscore templating handles arbitrary delimiters, preserves whitespace,
1086	  // and correctly escapes quotes within interpolated code.
1087	  _.template = function(text, data, settings) {
1088	    settings = _.defaults({}, settings, _.templateSettings);
1089	
1090	    // Combine delimiters into one regular expression via alternation.
1091	    var matcher = new RegExp([
1092	      (settings.escape || noMatch).source,
1093	      (settings.interpolate || noMatch).source,
1094	      (settings.evaluate || noMatch).source
1095	    ].join('|') + '|$', 'g');
1096	
1097	    // Compile the template source, escaping string literals appropriately.
1098	    var index = 0;
1099	    var source = "__p+='";
1100	    text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
1101	      source += text.slice(index, offset)
1102	        .replace(escaper, function(match) { return '\\' + escapes[match]; });
1103	      source +=
1104	        escape ? "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'" :
1105	        interpolate ? "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'" :
1106	        evaluate ? "';\n" + evaluate + "\n__p+='" : '';
1107	      index = offset + match.length;
1108	    });
1109	    source += "';\n";
1110	
1111	    // If a variable is not specified, place data values in local scope.
1112	    if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
1113	
1114	    source = "var __t,__p='',__j=Array.prototype.join," +
1115	      "print=function(){__p+=__j.call(arguments,'');};\n" +
1116	      source + "return __p;\n";
1117	
1118	    try {
1119	      var render = new Function(settings.variable || 'obj', '_', source);
1120	    } catch (e) {
1121	      e.source = source;
1122	      throw e;
1123	    }
1124	
1125	    if (data) return render(data, _);
1126	    var template = function(data) {
1127	      return render.call(this, data, _);
1128	    };
1129	
1130	    // Provide the compiled function source as a convenience for precompilation.
1131	    template.source = 'function(' + (settings.variable || 'obj') + '){\n' + source + '}';
1132	
1133	    return template;
1134	  };
1135	
1136	  // Add a "chain" function, which will delegate to the wrapper.
1137	  _.chain = function(obj) {
1138	    return _(obj).chain();
1139	  };
1140	
1141	  // OOP
1142	  // ---------------
1143	  // If Underscore is called as a function, it returns a wrapped object that
1144	  // can be used OO-style. This wrapper holds altered versions of all the
1145	  // underscore functions. Wrapped objects may be chained.
1146	
1147	  // Helper function to continue chaining intermediate results.
1148	  var result = function(obj) {
1149	    return this._chain ? _(obj).chain() : obj;
1150	  };
1151	
1152	  // Add all of the Underscore functions to the wrapper object.
1153	  _.mixin(_);
1154	
1155	  // Add all mutator Array functions to the wrapper.
1156	  each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
1157	    var method = ArrayProto[name];
1158	    _.prototype[name] = function() {
1159	      var obj = this._wrapped;
1160	      method.apply(obj, arguments);
1161	      if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
1162	      return result.call(this, obj);
1163	    };
1164	  });
1165	
1166	  // Add all accessor Array functions to the wrapper.
1167	  each(['concat', 'join', 'slice'], function(name) {
1168	    var method = ArrayProto[name];
1169	    _.prototype[name] = function() {
1170	      return result.call(this, method.apply(this._wrapped, arguments));
1171	    };
1172	  });
1173	
1174	  _.extend(_.prototype, {
1175	
1176	    // Start chaining a wrapped Underscore object.
1177	    chain: function() {
1178	      this._chain = true;
1179	      return this;
1180	    },
1181	
1182	    // Extracts the result from a wrapped and chained object.
1183	    value: function() {
1184	      return this._wrapped;
1185	    }
1186	
1187	  });
1188	
1189	}).call(this);

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