//     Underscore.js 1.2.2
  //     (c) 2011 Jeremy Ashkenas, DocumentCloud Inc.
  //     Underscore is freely distributable under the MIT license.
  //     Portions of Underscore are inspired or borrowed from Prototype,
  //     Oliver Steele's Functional, and John Resig's Micro-Templating.
  //     For all details and documentation:
  //     http://documentcloud.github.com/underscore
  
  (function() {
  
    // Baseline setup
    // --------------
  
    // Establish the root object, `window` in the browser, or `global` on the server.
    var root = this;
  
    // Save the previous value of the `_` variable.
    var previousUnderscore = root._;
  
    // Establish the object that gets returned to break out of a loop iteration.
    var breaker = {};
  
    // Save bytes in the minified (but not gzipped) version:
    var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
  
    // Create quick reference variables for speed access to core prototypes.
    var slice            = ArrayProto.slice,
        unshift          = ArrayProto.unshift,
        toString         = ObjProto.toString,
        hasOwnProperty   = ObjProto.hasOwnProperty;
  
    // All **ECMAScript 5** native function implementations that we hope to use
    // are declared here.
    var
      nativeForEach      = ArrayProto.forEach,
      nativeMap          = ArrayProto.map,
      nativeReduce       = ArrayProto.reduce,
      nativeReduceRight  = ArrayProto.reduceRight,
      nativeFilter       = ArrayProto.filter,
      nativeEvery        = ArrayProto.every,
      nativeSome         = ArrayProto.some,
      nativeIndexOf      = ArrayProto.indexOf,
      nativeLastIndexOf  = ArrayProto.lastIndexOf,
      nativeIsArray      = Array.isArray,
      nativeKeys         = Object.keys,
      nativeBind         = FuncProto.bind;
  
    // Create a safe reference to the Underscore object for use below.
    var _ = function(obj) { return new wrapper(obj); };
  
    // Export the Underscore object for **Node.js** and **"CommonJS"**, with
    // backwards-compatibility for the old `require()` API. If we're not in
    // CommonJS, add `_` to the global object.
    if (typeof exports !== 'undefined') {
      if (typeof module !== 'undefined' && module.exports) {
        exports = module.exports = _;
      }
      exports._ = _;
    } else if (typeof define === 'function' && define.amd) {
      // Register as a named module with AMD.
      define('underscore', function() {
        return _;
      });
    } else {
      // Exported as a string, for Closure Compiler "advanced" mode.
      root['_'] = _;
    }
  
    // Current version.
    _.VERSION = '1.2.2';
  
    // Collection Functions
    // --------------------
  
    // The cornerstone, an `each` implementation, aka `forEach`.
    // Handles objects with the built-in `forEach`, arrays, and raw objects.
    // Delegates to **ECMAScript 5**'s native `forEach` if available.
    var each = _.each = _.forEach = function(obj, iterator, context) {
      if (obj == null) return;
      if (nativeForEach && obj.forEach === nativeForEach) {
        obj.forEach(iterator, context);
      } else if (obj.length === +obj.length) {
        for (var i = 0, l = obj.length; i < l; i++) {
          if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
        }
      } else {
        for (var key in obj) {
          if (hasOwnProperty.call(obj, key)) {
            if (iterator.call(context, obj[key], key, obj) === breaker) return;
          }
        }
      }
    };
  
    // Return the results of applying the iterator to each element.
    // Delegates to **ECMAScript 5**'s native `map` if available.
    _.map = function(obj, iterator, context) {
      var results = [];
      if (obj == null) return results;
      if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
      each(obj, function(value, index, list) {
        results[results.length] = iterator.call(context, value, index, list);
      });
      return results;
    };
  
    // **Reduce** builds up a single result from a list of values, aka `inject`,
    // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
    _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
      var initial = memo !== void 0;
      if (obj == null) obj = [];
      if (nativeReduce && obj.reduce === nativeReduce) {
        if (context) iterator = _.bind(iterator, context);
        return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
      }
      each(obj, function(value, index, list) {
        if (!initial) {
          memo = value;
          initial = true;
        } else {
          memo = iterator.call(context, memo, value, index, list);
        }
      });
      if (!initial) throw new TypeError("Reduce of empty array with no initial value");
      return memo;
    };
  
    // The right-associative version of reduce, also known as `foldr`.
    // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
    _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
      if (obj == null) obj = [];
      if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
        if (context) iterator = _.bind(iterator, context);
        return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
      }
      var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();
      return _.reduce(reversed, iterator, memo, context);
    };
  
    // Return the first value which passes a truth test. Aliased as `detect`.
    _.find = _.detect = function(obj, iterator, context) {
      var result;
      any(obj, function(value, index, list) {
        if (iterator.call(context, value, index, list)) {
          result = value;
          return true;
        }
      });
      return result;
    };
  
    // Return all the elements that pass a truth test.
    // Delegates to **ECMAScript 5**'s native `filter` if available.
    // Aliased as `select`.
    _.filter = _.select = function(obj, iterator, context) {
      var results = [];
      if (obj == null) return results;
      if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
      each(obj, function(value, index, list) {
        if (iterator.call(context, value, index, list)) results[results.length] = value;
      });
      return results;
    };
  
    // Return all the elements for which a truth test fails.
    _.reject = function(obj, iterator, context) {
      var results = [];
      if (obj == null) return results;
      each(obj, function(value, index, list) {
        if (!iterator.call(context, value, index, list)) results[results.length] = value;
      });
      return results;
    };
  
    // Determine whether all of the elements match a truth test.
    // Delegates to **ECMAScript 5**'s native `every` if available.
    // Aliased as `all`.
    _.every = _.all = function(obj, iterator, context) {
      var result = true;
      if (obj == null) return result;
      if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
      each(obj, function(value, index, list) {
        if (!(result = result && iterator.call(context, value, index, list))) return breaker;
      });
      return result;
    };
  
    // Determine if at least one element in the object matches a truth test.
    // Delegates to **ECMAScript 5**'s native `some` if available.
    // Aliased as `any`.
    var any = _.some = _.any = function(obj, iterator, context) {
      iterator = iterator || _.identity;
      var result = false;
      if (obj == null) return result;
      if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
      each(obj, function(value, index, list) {
        if (result || (result = iterator.call(context, value, index, list))) return breaker;
      });
      return !!result;
    };
  
    // Determine if a given value is included in the array or object using `===`.
    // Aliased as `contains`.
    _.include = _.contains = function(obj, target) {
      var found = false;
      if (obj == null) return found;
      if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
      found = any(obj, function(value) {
        return value === target;
      });
      return found;
    };
  
    // Invoke a method (with arguments) on every item in a collection.
    _.invoke = function(obj, method) {
      var args = slice.call(arguments, 2);
      return _.map(obj, function(value) {
        return (method.call ? method || value : value[method]).apply(value, args);
      });
    };
  
    // Convenience version of a common use case of `map`: fetching a property.
    _.pluck = function(obj, key) {
      return _.map(obj, function(value){ return value[key]; });
    };
  
    // Return the maximum element or (element-based computation).
    _.max = function(obj, iterator, context) {
      if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);
      if (!iterator && _.isEmpty(obj)) return -Infinity;
      var result = {computed : -Infinity};
      each(obj, function(value, index, list) {
        var computed = iterator ? iterator.call(context, value, index, list) : value;
        computed >= result.computed && (result = {value : value, computed : computed});
      });
      return result.value;
    };
  
    // Return the minimum element (or element-based computation).
    _.min = function(obj, iterator, context) {
      if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);
      if (!iterator && _.isEmpty(obj)) return Infinity;
      var result = {computed : Infinity};
      each(obj, function(value, index, list) {
        var computed = iterator ? iterator.call(context, value, index, list) : value;
        computed < result.computed && (result = {value : value, computed : computed});
      });
      return result.value;
    };
  
    // Shuffle an array.
    _.shuffle = function(obj) {
      var shuffled = [], rand;
      each(obj, function(value, index, list) {
        if (index == 0) {
          shuffled[0] = value;
        } else {
          rand = Math.floor(Math.random() * (index + 1));
          shuffled[index] = shuffled[rand];
          shuffled[rand] = value;
        }
      });
      return shuffled;
    };
  
    // Sort the object's values by a criterion produced by an iterator.
    _.sortBy = function(obj, iterator, context) {
      return _.pluck(_.map(obj, function(value, index, list) {
        return {
          value : value,
          criteria : iterator.call(context, value, index, list)
        };
      }).sort(function(left, right) {
        var a = left.criteria, b = right.criteria;
        return a < b ? -1 : a > b ? 1 : 0;
      }), 'value');
    };
  
    // Groups the object's values by a criterion. Pass either a string attribute
    // to group by, or a function that returns the criterion.
    _.groupBy = function(obj, val) {
      var result = {};
      var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };
      each(obj, function(value, index) {
        var key = iterator(value, index);
        (result[key] || (result[key] = [])).push(value);
      });
      return result;
    };
  
    // Use a comparator function to figure out at what index an object should
    // be inserted so as to maintain order. Uses binary search.
    _.sortedIndex = function(array, obj, iterator) {
      iterator || (iterator = _.identity);
      var low = 0, high = array.length;
      while (low < high) {
        var mid = (low + high) >> 1;
        iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
      }
      return low;
    };
  
    // Safely convert anything iterable into a real, live array.
    _.toArray = function(iterable) {
      if (!iterable)                return [];
      if (iterable.toArray)         return iterable.toArray();
      if (_.isArray(iterable))      return slice.call(iterable);
      if (_.isArguments(iterable))  return slice.call(iterable);
      return _.values(iterable);
    };
  
    // Return the number of elements in an object.
    _.size = function(obj) {
      return _.toArray(obj).length;
    };
  
    // Array Functions
    // ---------------
  
    // Get the first element of an array. Passing **n** will return the first N
    // values in the array. Aliased as `head`. The **guard** check allows it to work
    // with `_.map`.
    _.first = _.head = function(array, n, guard) {
      return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
    };
  
    // Returns everything but the last entry of the array. Especcialy useful on
    // the arguments object. Passing **n** will return all the values in
    // the array, excluding the last N. The **guard** check allows it to work with
    // `_.map`.
    _.initial = function(array, n, guard) {
      return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
    };
  
    // Get the last element of an array. Passing **n** will return the last N
    // values in the array. The **guard** check allows it to work with `_.map`.
    _.last = function(array, n, guard) {
      if ((n != null) && !guard) {
        return slice.call(array, Math.max(array.length - n, 0));
      } else {
        return array[array.length - 1];
      }
    };
  
    // Returns everything but the first entry of the array. Aliased as `tail`.
    // Especially useful on the arguments object. Passing an **index** will return
    // the rest of the values in the array from that index onward. The **guard**
    // check allows it to work with `_.map`.
    _.rest = _.tail = function(array, index, guard) {
      return slice.call(array, (index == null) || guard ? 1 : index);
    };
  
    // Trim out all falsy values from an array.
    _.compact = function(array) {
      return _.filter(array, function(value){ return !!value; });
    };
  
    // Return a completely flattened version of an array.
    _.flatten = function(array, shallow) {
      return _.reduce(array, function(memo, value) {
        if (_.isArray(value)) return memo.concat(shallow ? value : _.flatten(value));
        memo[memo.length] = value;
        return memo;
      }, []);
    };
  
    // Return a version of the array that does not contain the specified value(s).
    _.without = function(array) {
      return _.difference(array, slice.call(arguments, 1));
    };
  
    // Produce a duplicate-free version of the array. If the array has already
    // been sorted, you have the option of using a faster algorithm.
    // Aliased as `unique`.
    _.uniq = _.unique = function(array, isSorted, iterator) {
      var initial = iterator ? _.map(array, iterator) : array;
      var result = [];
      _.reduce(initial, function(memo, el, i) {
        if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) {
          memo[memo.length] = el;
          result[result.length] = array[i];
        }
        return memo;
      }, []);
      return result;
    };
  
    // Produce an array that contains the union: each distinct element from all of
    // the passed-in arrays.
    _.union = function() {
      return _.uniq(_.flatten(arguments, true));
    };
  
    // Produce an array that contains every item shared between all the
    // passed-in arrays. (Aliased as "intersect" for back-compat.)
    _.intersection = _.intersect = function(array) {
      var rest = slice.call(arguments, 1);
      return _.filter(_.uniq(array), function(item) {
        return _.every(rest, function(other) {
          return _.indexOf(other, item) >= 0;
        });
      });
    };
  
    // Take the difference between one array and another.
    // Only the elements present in just the first array will remain.
    _.difference = function(array, other) {
      return _.filter(array, function(value){ return !_.include(other, value); });
    };
  
    // Zip together multiple lists into a single array -- elements that share
    // an index go together.
    _.zip = function() {
      var args = slice.call(arguments);
      var length = _.max(_.pluck(args, 'length'));
      var results = new Array(length);
      for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
      return results;
    };
  
    // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
    // we need this function. Return the position of the first occurrence of an
    // item in an array, or -1 if the item is not included in the array.
    // Delegates to **ECMAScript 5**'s native `indexOf` if available.
    // If the array is large and already in sort order, pass `true`
    // for **isSorted** to use binary search.
    _.indexOf = function(array, item, isSorted) {
      if (array == null) return -1;
      var i, l;
      if (isSorted) {
        i = _.sortedIndex(array, item);
        return array[i] === item ? i : -1;
      }
      if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
      for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
      return -1;
    };
  
    // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
    _.lastIndexOf = function(array, item) {
      if (array == null) return -1;
      if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
      var i = array.length;
      while (i--) if (array[i] === item) return i;
      return -1;
    };
  
    // Generate an integer Array containing an arithmetic progression. A port of
    // the native Python `range()` function. See
    // [the Python documentation](http://docs.python.org/library/functions.html#range).
    _.range = function(start, stop, step) {
      if (arguments.length <= 1) {
        stop = start || 0;
        start = 0;
      }
      step = arguments[2] || 1;
  
      var len = Math.max(Math.ceil((stop - start) / step), 0);
      var idx = 0;
      var range = new Array(len);
  
      while(idx < len) {
        range[idx++] = start;
        start += step;
      }
  
      return range;
    };
  
    // Function (ahem) Functions
    // ------------------
  
    // Reusable constructor function for prototype setting.
    var ctor = function(){};
  
    // Create a function bound to a given object (assigning `this`, and arguments,
    // optionally). Binding with arguments is also known as `curry`.
    // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
    // We check for `func.bind` first, to fail fast when `func` is undefined.
    _.bind = function bind(func, context) {
      var bound, args;
      if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
      if (!_.isFunction(func)) throw new TypeError;
      args = slice.call(arguments, 2);
      return bound = function() {
        if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
        ctor.prototype = func.prototype;
        var self = new ctor;
        var result = func.apply(self, args.concat(slice.call(arguments)));
        if (Object(result) === result) return result;
        return self;
      };
    };
  
    // Bind all of an object's methods to that object. Useful for ensuring that
    // all callbacks defined on an object belong to it.
    _.bindAll = function(obj) {
      var funcs = slice.call(arguments, 1);
      if (funcs.length == 0) funcs = _.functions(obj);
      each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
      return obj;
    };
  
    // Memoize an expensive function by storing its results.
    _.memoize = function(func, hasher) {
      var memo = {};
      hasher || (hasher = _.identity);
      return function() {
        var key = hasher.apply(this, arguments);
        return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
      };
    };
  
    // Delays a function for the given number of milliseconds, and then calls
    // it with the arguments supplied.
    _.delay = function(func, wait) {
      var args = slice.call(arguments, 2);
      return setTimeout(function(){ return func.apply(func, args); }, wait);
    };
  
    // Defers a function, scheduling it to run after the current call stack has
    // cleared.
    _.defer = function(func) {
      return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
    };
  
    // Returns a function, that, when invoked, will only be triggered at most once
    // during a given window of time.
    _.throttle = function(func, wait) {
      var context, args, timeout, throttling, more;
      var whenDone = _.debounce(function(){ more = throttling = false; }, wait);
      return function() {
        context = this; args = arguments;
        var later = function() {
          timeout = null;
          if (more) func.apply(context, args);
          whenDone();
        };
        if (!timeout) timeout = setTimeout(later, wait);
        if (throttling) {
          more = true;
        } else {
          func.apply(context, args);
        }
        whenDone();
        throttling = true;
      };
    };
  
    // Returns a function, that, as long as it continues to be invoked, will not
    // be triggered. The function will be called after it stops being called for
    // N milliseconds.
    _.debounce = function(func, wait) {
      var timeout;
      return function() {
        var context = this, args = arguments;
        var later = function() {
          timeout = null;
          func.apply(context, args);
        };
        clearTimeout(timeout);
        timeout = setTimeout(later, wait);
      };
    };
  
    // Returns a function that will be executed at most one time, no matter how
    // often you call it. Useful for lazy initialization.
    _.once = function(func) {
      var ran = false, memo;
      return function() {
        if (ran) return memo;
        ran = true;
        return memo = func.apply(this, arguments);
      };
    };
  
    // Returns the first function passed as an argument to the second,
    // allowing you to adjust arguments, run code before and after, and
    // conditionally execute the original function.
    _.wrap = function(func, wrapper) {
      return function() {
        var args = [func].concat(slice.call(arguments));
        return wrapper.apply(this, args);
      };
    };
  
    // Returns a function that is the composition of a list of functions, each
    // consuming the return value of the function that follows.
    _.compose = function() {
      var funcs = slice.call(arguments);
      return function() {
        var args = slice.call(arguments);
        for (var i = funcs.length - 1; i >= 0; i--) {
          args = [funcs[i].apply(this, args)];
        }
        return args[0];
      };
    };
  
    // Returns a function that will only be executed after being called N times.
    _.after = function(times, func) {
      if (times <= 0) return func();
      return function() {
        if (--times < 1) { return func.apply(this, arguments); }
      };
    };
  
    // Object Functions
    // ----------------
  
    // Retrieve the names of an object's properties.
    // Delegates to **ECMAScript 5**'s native `Object.keys`
    _.keys = nativeKeys || function(obj) {
      if (obj !== Object(obj)) throw new TypeError('Invalid object');
      var keys = [];
      for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;
      return keys;
    };
  
    // Retrieve the values of an object's properties.
    _.values = function(obj) {
      return _.map(obj, _.identity);
    };
  
    // Return a sorted list of the function names available on the object.
    // Aliased as `methods`
    _.functions = _.methods = function(obj) {
      var names = [];
      for (var key in obj) {
        if (_.isFunction(obj[key])) names.push(key);
      }
      return names.sort();
    };
  
    // Extend a given object with all the properties in passed-in object(s).
    _.extend = function(obj) {
      each(slice.call(arguments, 1), function(source) {
        for (var prop in source) {
          if (source[prop] !== void 0) obj[prop] = source[prop];
        }
      });
      return obj;
    };
  
    // Fill in a given object with default properties.
    _.defaults = function(obj) {
      each(slice.call(arguments, 1), function(source) {
        for (var prop in source) {
          if (obj[prop] == null) obj[prop] = source[prop];
        }
      });
      return obj;
    };
  
    // Create a (shallow-cloned) duplicate of an object.
    _.clone = function(obj) {
      if (!_.isObject(obj)) return obj;
      return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
    };
  
    // Invokes interceptor with the obj, and then returns obj.
    // The primary purpose of this method is to "tap into" a method chain, in
    // order to perform operations on intermediate results within the chain.
    _.tap = function(obj, interceptor) {
      interceptor(obj);
      return obj;
    };
  
    // Internal recursive comparison function.
    function eq(a, b, stack) {
      // Identical objects are equal. `0 === -0`, but they aren't identical.
      // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.
      if (a === b) return a !== 0 || 1 / a == 1 / b;
      // A strict comparison is necessary because `null == undefined`.
      if (a == null || b == null) return a === b;
      // Unwrap any wrapped objects.
      if (a._chain) a = a._wrapped;
      if (b._chain) b = b._wrapped;
      // Invoke a custom `isEqual` method if one is provided.
      if (_.isFunction(a.isEqual)) return a.isEqual(b);
      if (_.isFunction(b.isEqual)) return b.isEqual(a);
      // Compare `[[Class]]` names.
      var className = toString.call(a);
      if (className != toString.call(b)) return false;
      switch (className) {
        // Strings, numbers, dates, and booleans are compared by value.
        case '[object String]':
          // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
          // equivalent to `new String("5")`.
          return String(a) == String(b);
        case '[object Number]':
          a = +a;
          b = +b;
          // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
          // other numeric values.
          return a != a ? b != b : (a == 0 ? 1 / a == 1 / b : a == b);
        case '[object Date]':
        case '[object Boolean]':
          // Coerce dates and booleans to numeric primitive values. Dates are compared by their
          // millisecond representations. Note that invalid dates with millisecond representations
          // of `NaN` are not equivalent.
          return +a == +b;
        // RegExps are compared by their source patterns and flags.
        case '[object RegExp]':
          return a.source == b.source &&
                 a.global == b.global &&
                 a.multiline == b.multiline &&
                 a.ignoreCase == b.ignoreCase;
      }
      if (typeof a != 'object' || typeof b != 'object') return false;
      // Assume equality for cyclic structures. The algorithm for detecting cyclic
      // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
      var length = stack.length;
      while (length--) {
        // Linear search. Performance is inversely proportional to the number of
        // unique nested structures.
        if (stack[length] == a) return true;
      }
      // Add the first object to the stack of traversed objects.
      stack.push(a);
      var size = 0, result = true;
      // Recursively compare objects and arrays.
      if (className == '[object Array]') {
        // Compare array lengths to determine if a deep comparison is necessary.
        size = a.length;
        result = size == b.length;
        if (result) {
          // Deep compare the contents, ignoring non-numeric properties.
          while (size--) {
            // Ensure commutative equality for sparse arrays.
            if (!(result = size in a == size in b && eq(a[size], b[size], stack))) break;
          }
        }
      } else {
        // Objects with different constructors are not equivalent.
        if ("constructor" in a != "constructor" in b || a.constructor != b.constructor) return false;
        // Deep compare objects.
        for (var key in a) {
          if (hasOwnProperty.call(a, key)) {
            // Count the expected number of properties.
            size++;
            // Deep compare each member.
            if (!(result = hasOwnProperty.call(b, key) && eq(a[key], b[key], stack))) break;
          }
        }
        // Ensure that both objects contain the same number of properties.
        if (result) {
          for (key in b) {
            if (hasOwnProperty.call(b, key) && !(size--)) break;
          }
          result = !size;
        }
      }
      // Remove the first object from the stack of traversed objects.
      stack.pop();
      return result;
    }
  
    // Perform a deep comparison to check if two objects are equal.
    _.isEqual = function(a, b) {
      return eq(a, b, []);
    };
  
    // Is a given array, string, or object empty?
    // An "empty" object has no enumerable own-properties.
    _.isEmpty = function(obj) {
      if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
      for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;
      return true;
    };
  
    // Is a given value a DOM element?
    _.isElement = function(obj) {
      return !!(obj && obj.nodeType == 1);
    };
  
    // Is a given value an array?
    // Delegates to ECMA5's native Array.isArray
    _.isArray = nativeIsArray || function(obj) {
      return toString.call(obj) == '[object Array]';
    };
  
    // Is a given variable an object?
    _.isObject = function(obj) {
      return obj === Object(obj);
    };
  
    // Is a given variable an arguments object?
    if (toString.call(arguments) == '[object Arguments]') {
      _.isArguments = function(obj) {
        return toString.call(obj) == '[object Arguments]';
      };
    } else {
      _.isArguments = function(obj) {
        return !!(obj && hasOwnProperty.call(obj, 'callee'));
      };
    }
  
    // Is a given value a function?
    _.isFunction = function(obj) {
      return toString.call(obj) == '[object Function]';
    };
  
    // Is a given value a string?
    _.isString = function(obj) {
      return toString.call(obj) == '[object String]';
    };
  
    // Is a given value a number?
    _.isNumber = function(obj) {
      return toString.call(obj) == '[object Number]';
    };
  
    // Is the given value `NaN`?
    _.isNaN = function(obj) {
      // `NaN` is the only value for which `===` is not reflexive.
      return obj !== obj;
    };
  
    // Is a given value a boolean?
    _.isBoolean = function(obj) {
      return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
    };
  
    // Is a given value a date?
    _.isDate = function(obj) {
      return toString.call(obj) == '[object Date]';
    };
  
    // Is the given value a regular expression?
    _.isRegExp = function(obj) {
      return toString.call(obj) == '[object RegExp]';
    };
  
    // Is a given value equal to null?
    _.isNull = function(obj) {
      return obj === null;
    };
  
    // Is a given variable undefined?
    _.isUndefined = function(obj) {
      return obj === void 0;
    };
  
    // Utility Functions
    // -----------------
  
    // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
    // previous owner. Returns a reference to the Underscore object.
    _.noConflict = function() {
      root._ = previousUnderscore;
      return this;
    };
  
    // Keep the identity function around for default iterators.
    _.identity = function(value) {
      return value;
    };
  
    // Run a function **n** times.
    _.times = function (n, iterator, context) {
      for (var i = 0; i < n; i++) iterator.call(context, i);
    };
  
    // Escape a string for HTML interpolation.
    _.escape = function(string) {
      return (''+string).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#x27;').replace(/\//g,'&#x2F;');
    };
  
    // Add your own custom functions to the Underscore object, ensuring that
    // they're correctly added to the OOP wrapper as well.
    _.mixin = function(obj) {
      each(_.functions(obj), function(name){
        addToWrapper(name, _[name] = obj[name]);
      });
    };
  
    // Generate a unique integer id (unique within the entire client session).
    // Useful for temporary DOM ids.
    var idCounter = 0;
    _.uniqueId = function(prefix) {
      var id = idCounter++;
      return prefix ? prefix + id : id;
    };
  
    // By default, Underscore uses ERB-style template delimiters, change the
    // following template settings to use alternative delimiters.
    _.templateSettings = {
      evaluate    : /<%([\s\S]+?)%>/g,
      interpolate : /<%=([\s\S]+?)%>/g,
      escape      : /<%-([\s\S]+?)%>/g
    };
  
    // JavaScript micro-templating, similar to John Resig's implementation.
    // Underscore templating handles arbitrary delimiters, preserves whitespace,
    // and correctly escapes quotes within interpolated code.
    _.template = function(str, data) {
      var c  = _.templateSettings;
      var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
        'with(obj||{}){__p.push(\'' +
        str.replace(/\\/g, '\\\\')
           .replace(/'/g, "\\'")
           .replace(c.escape, function(match, code) {
             return "',_.escape(" + code.replace(/\\'/g, "'") + "),'";
           })
           .replace(c.interpolate, function(match, code) {
             return "'," + code.replace(/\\'/g, "'") + ",'";
           })
           .replace(c.evaluate || null, function(match, code) {
             return "');" + code.replace(/\\'/g, "'")
                                .replace(/[\r\n\t]/g, ' ') + ";__p.push('";
           })
           .replace(/\r/g, '\\r')
           .replace(/\n/g, '\\n')
           .replace(/\t/g, '\\t')
           + "');}return __p.join('');";
      var func = new Function('obj', '_', tmpl);
      return data ? func(data, _) : function(data) { return func(data, _) };
    };
  
    // The OOP Wrapper
    // ---------------
  
    // If Underscore is called as a function, it returns a wrapped object that
    // can be used OO-style. This wrapper holds altered versions of all the
    // underscore functions. Wrapped objects may be chained.
    var wrapper = function(obj) { this._wrapped = obj; };
  
    // Expose `wrapper.prototype` as `_.prototype`
    _.prototype = wrapper.prototype;
  
    // Helper function to continue chaining intermediate results.
    var result = function(obj, chain) {
      return chain ? _(obj).chain() : obj;
    };
  
    // A method to easily add functions to the OOP wrapper.
    var addToWrapper = function(name, func) {
      wrapper.prototype[name] = function() {
        var args = slice.call(arguments);
        unshift.call(args, this._wrapped);
        return result(func.apply(_, args), this._chain);
      };
    };
  
    // Add all of the Underscore functions to the wrapper object.
    _.mixin(_);
  
    // Add all mutator Array functions to the wrapper.
    each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
      var method = ArrayProto[name];
      wrapper.prototype[name] = function() {
        method.apply(this._wrapped, arguments);
        return result(this._wrapped, this._chain);
      };
    });
  
    // Add all accessor Array functions to the wrapper.
    each(['concat', 'join', 'slice'], function(name) {
      var method = ArrayProto[name];
      wrapper.prototype[name] = function() {
        return result(method.apply(this._wrapped, arguments), this._chain);
      };
    });
  
    // Start chaining a wrapped Underscore object.
    wrapper.prototype.chain = function() {
      this._chain = true;
      return this;
    };
  
    // Extracts the result from a wrapped and chained object.
    wrapper.prototype.value = function() {
      return this._wrapped;
    };
  
  }).call(this);