zikula / core

(function() {

  // Baseline setup

  // --------------

  // Establish the root object, `window` in the browser, or `exports` on the server.

  var root = this;

  // Save the previous value of the `_` variable.

  var previousUnderscore = root._;

  // 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

    push             = ArrayProto.push,

    slice            = ArrayProto.slice,

    toString         = ObjProto.toString,

    hasOwnProperty   = ObjProto.hasOwnProperty;

  // All **ECMAScript 5** native function implementations that we hope to use

  // are declared here.

  var

    nativeIsArray      = Array.isArray,

    nativeKeys         = Object.keys,

    nativeBind         = FuncProto.bind,

    nativeCreate       = Object.create;

  // Naked function reference for surrogate-prototype-swapping.

  var Ctor = function(){};

  // Create a safe reference to the Underscore object for use below.

  var _ = function(obj) {

    if (obj instanceof _) return obj;

    if (!(this instanceof _)) return new _(obj);

  };

  // Export the Underscore object for **Node.js**, with

  // backwards-compatibility for the old `require()` API. If we're in

  // the browser, add `_` as a global object.

  if (typeof exports !== 'undefined') {

    if (typeof module !== 'undefined' && module.exports) {

      exports = module.exports = _;

    }

    exports._ = _;

  } else {

    root._ = _;

  }

  // Current version.

  _.VERSION = '1.8.3';

  // Internal function that returns an efficient (for current engines) version

  // of the passed-in callback, to be repeatedly applied in other Underscore

  // functions.

  var optimizeCb = function(func, context, argCount) {

      case 1: return function(value) {

        return func.call(context, value);

      };

      case 2: return function(value, other) {

        return func.call(context, value, other);

      };

      case 3: return function(value, index, collection) {

        return func.call(context, value, index, collection);

      };

      case 4: return function(accumulator, value, index, collection) {

        return func.call(context, accumulator, value, index, collection);

      };

    }

    return function() {

      return func.apply(context, arguments);

    };

  };

  // A mostly-internal function to generate callbacks that can be applied

  // to each element in a collection, returning the desired result — either

  // identity, an arbitrary callback, a property matcher, or a property accessor.

  var cb = function(value, context, argCount) {

    if (value == null) return _.identity;

    if (_.isFunction(value)) return optimizeCb(value, context, argCount);

    if (_.isObject(value)) return _.matcher(value);

    return _.property(value);

  };

  _.iteratee = function(value, context) {

    return cb(value, context, Infinity);

  };

  // An internal function for creating assigner functions.

  var createAssigner = function(keysFunc, undefinedOnly) {

    return function(obj) {

      var length = arguments.length;

      if (length < 2 || obj == null) return obj;

      for (var index = 1; index < length; index++) {

        var source = arguments[index],

            keys = keysFunc(source),

            l = keys.length;

        for (var i = 0; i < l; i++) {

          var key = keys[i];

        }

      }

      return obj;

    };

  };

  // An internal function for creating a new object that inherits from another.

  var baseCreate = function(prototype) {

    if (!_.isObject(prototype)) return {};

    if (nativeCreate) return nativeCreate(prototype);

    Ctor.prototype = prototype;

    var result = new Ctor;

    Ctor.prototype = null;

    return result;

  };

  var property = function(key) {

    return function(obj) {

    };

  };

  // Helper for collection methods to determine whether a collection

  // should be iterated as an array or as an object

  // Related: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength

  // Avoids a very nasty iOS 8 JIT bug on ARM-64. #2094

  var MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;

  var getLength = property('length');

  var isArrayLike = function(collection) {

    var length = getLength(collection);

    return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;

  };

  // Collection Functions

  // --------------------

  // The cornerstone, an `each` implementation, aka `forEach`.

  // Handles raw objects in addition to array-likes. Treats all

  // sparse array-likes as if they were dense.

  _.each = _.forEach = function(obj, iteratee, context) {

    iteratee = optimizeCb(iteratee, context);

    var i, length;

    if (isArrayLike(obj)) {

      for (i = 0, length = obj.length; i < length; i++) {

        iteratee(obj[i], i, obj);

      }

    } else {

      var keys = _.keys(obj);

      for (i = 0, length = keys.length; i < length; i++) {

        iteratee(obj[keys[i]], keys[i], obj);

      }

    }

    return obj;

  };

  // Return the results of applying the iteratee to each element.

  _.map = _.collect = function(obj, iteratee, context) {

    iteratee = cb(iteratee, context);

    var keys = !isArrayLike(obj) && _.keys(obj),

        length = (keys || obj).length,

        results = Array(length);

    for (var index = 0; index < length; index++) {

      var currentKey = keys ? keys[index] : index;

      results[index] = iteratee(obj[currentKey], currentKey, obj);

    }

    return results;

  };

  // Create a reducing function iterating left or right.

  function createReduce(dir) {

    // Optimized iterator function as using arguments.length

    // in the main function will deoptimize the, see #1991.

    function iterator(obj, iteratee, memo, keys, index, length) {

      for (; index >= 0 && index < length; index += dir) {

        var currentKey = keys ? keys[index] : index;

        memo = iteratee(memo, obj[currentKey], currentKey, obj);

      }

      return memo;

    }

    return function(obj, iteratee, memo, context) {

      iteratee = optimizeCb(iteratee, context, 4);

      var keys = !isArrayLike(obj) && _.keys(obj),

          length = (keys || obj).length,

          index = dir > 0 ? 0 : length - 1;

      // Determine the initial value if none is provided.

      if (arguments.length < 3) {

        memo = obj[keys ? keys[index] : index];

        index += dir;

      }

      return iterator(obj, iteratee, memo, keys, index, length);

    };

  }

  // **Reduce** builds up a single result from a list of values, aka `inject`,

  // or `foldl`.

  _.reduce = _.foldl = _.inject = createReduce(1);

  // The right-associative version of reduce, also known as `foldr`.

  _.reduceRight = _.foldr = createReduce(-1);

  // Return the first value which passes a truth test. Aliased as `detect`.

  _.find = _.detect = function(obj, predicate, context) {

    var key;

    if (isArrayLike(obj)) {

      key = _.findIndex(obj, predicate, context);

    } else {

      key = _.findKey(obj, predicate, context);

    }

  };

  // Return all the elements that pass a truth test.

  // Aliased as `select`.

  _.filter = _.select = function(obj, predicate, context) {

    var results = [];

    predicate = cb(predicate, context);

    _.each(obj, function(value, index, list) {

      if (predicate(value, index, list)) results.push(value);

    });

    return results;

  };

  // Return all the elements for which a truth test fails.

  _.reject = function(obj, predicate, context) {

    return _.filter(obj, _.negate(cb(predicate)), context);

  };

  // Determine whether all of the elements match a truth test.

  // Aliased as `all`.

  _.every = _.all = function(obj, predicate, context) {

    predicate = cb(predicate, context);

    var keys = !isArrayLike(obj) && _.keys(obj),

        length = (keys || obj).length;

    for (var index = 0; index < length; index++) {

      var currentKey = keys ? keys[index] : index;

      if (!predicate(obj[currentKey], currentKey, obj)) return false;

    }

    return true;

  };

  // Determine if at least one element in the object matches a truth test.

  // Aliased as `any`.

  _.some = _.any = function(obj, predicate, context) {

    predicate = cb(predicate, context);

    var keys = !isArrayLike(obj) && _.keys(obj),

        length = (keys || obj).length;

    for (var index = 0; index < length; index++) {

      var currentKey = keys ? keys[index] : index;

      if (predicate(obj[currentKey], currentKey, obj)) return true;

    }

    return false;

  };

  // Determine if the array or object contains a given item (using `===`).

  // Aliased as `includes` and `include`.

  _.contains = _.includes = _.include = function(obj, item, fromIndex, guard) {

    if (!isArrayLike(obj)) obj = _.values(obj);

    if (typeof fromIndex != 'number' || guard) fromIndex = 0;

    return _.indexOf(obj, item, fromIndex) >= 0;

  };

  // Invoke a method (with arguments) on every item in a collection.

  _.invoke = function(obj, method) {

    var args = slice.call(arguments, 2);

    var isFunc = _.isFunction(method);

    return _.map(obj, function(value) {

      var func = isFunc ? method : value[method];

      return func == null ? func : func.apply(value, args);

    });

  };

  // Convenience version of a common use case of `map`: fetching a property.

  _.pluck = function(obj, key) {

    return _.map(obj, _.property(key));

  };

  // Convenience version of a common use case of `filter`: selecting only objects

  // containing specific `key:value` pairs.

  _.where = function(obj, attrs) {

    return _.filter(obj, _.matcher(attrs));

  };

  // Convenience version of a common use case of `find`: getting the first object

  // containing specific `key:value` pairs.

  _.findWhere = function(obj, attrs) {

    return _.find(obj, _.matcher(attrs));

  };

  // Return the maximum element (or element-based computation).

    var result = -Infinity, lastComputed = -Infinity,

        value, computed;

    if (iteratee == null && obj != null) {

      obj = isArrayLike(obj) ? obj : _.values(obj);

      for (var i = 0, length = obj.length; i < length; i++) {

        value = obj[i];

        if (value > result) {

          result = value;

        }

      }

    } else {

      iteratee = cb(iteratee, context);

      _.each(obj, function(value, index, list) {

        computed = iteratee(value, index, list);

        if (computed > lastComputed || computed === -Infinity && result === -Infinity) {

          result = value;

          lastComputed = computed;

        }

      });

    }

    return result;

  };

  // Return the minimum element (or element-based computation).

        value, computed;

    if (iteratee == null && obj != null) {

      obj = isArrayLike(obj) ? obj : _.values(obj);

      for (var i = 0, length = obj.length; i < length; i++) {

        value = obj[i];

        if (value < result) {

          result = value;

        }

      }

    } else {

      iteratee = cb(iteratee, context);

      _.each(obj, function(value, index, list) {

        computed = iteratee(value, index, list);

        if (computed < lastComputed || computed === Infinity && result === Infinity) {

          result = value;

          lastComputed = computed;

        }

      });

    }

    return result;

  };

  // Shuffle a collection, using the modern version of the

  // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).

  _.shuffle = function(obj) {

    var set = isArrayLike(obj) ? obj : _.values(obj);

    var length = set.length;

    var shuffled = Array(length);

    for (var index = 0, rand; index < length; index++) {

      rand = _.random(0, index);

      if (rand !== index) shuffled[index] = shuffled[rand];

      shuffled[rand] = set[index];

    }

    return shuffled;

  };

  // Sample **n** random values from a collection.

  // If **n** is not specified, returns a single random element.

  // The internal `guard` argument allows it to work with `map`.

  _.sample = function(obj, n, guard) {

    if (n == null || guard) {

      if (!isArrayLike(obj)) obj = _.values(obj);

      return obj[_.random(obj.length - 1)];

    }

    return _.shuffle(obj).slice(0, Math.max(0, n));

  };

  // Sort the object's values by a criterion produced by an iteratee.

  _.sortBy = function(obj, iteratee, context) {

    iteratee = cb(iteratee, context);

    return _.pluck(_.map(obj, function(value, index, list) {

      return {

        value: value,

        index: index,

        criteria: iteratee(value, index, list)

      };

    }).sort(function(left, right) {

      var a = left.criteria;

      var b = right.criteria;

      if (a !== b) {

      }

      return left.index - right.index;

    }), 'value');

  };

  // An internal function used for aggregate "group by" operations.

  var group = function(behavior) {

    return function(obj, iteratee, context) {

      var result = {};

      iteratee = cb(iteratee, context);

      _.each(obj, function(value, index) {

        var key = iteratee(value, index, obj);

        behavior(result, value, key);

      });

      return result;

    };

  };

  // Groups the object's values by a criterion. Pass either a string attribute

  // to group by, or a function that returns the criterion.

  _.groupBy = group(function(result, value, key) {

    if (_.has(result, key)) result[key].push(value); else result[key] = [value];

  });

  // Indexes the object's values by a criterion, similar to `groupBy`, but for

  // when you know that your index values will be unique.

  _.indexBy = group(function(result, value, key) {

    result[key] = value;

  });

  // Counts instances of an object that group by a certain criterion. Pass

  // either a string attribute to count by, or a function that returns the

  // criterion.

  _.countBy = group(function(result, value, key) {

    if (_.has(result, key)) result[key]++; else result[key] = 1;

  });

  // Safely create a real, live array from anything iterable.

  _.toArray = function(obj) {

    if (!obj) return [];

    if (_.isArray(obj)) return slice.call(obj);

    if (isArrayLike(obj)) return _.map(obj, _.identity);

    return _.values(obj);

  };

  // Return the number of elements in an object.

  _.size = function(obj) {

    if (obj == null) return 0;

    return isArrayLike(obj) ? obj.length : _.keys(obj).length;

  };

  // Split a collection into two arrays: one whose elements all satisfy the given

  // predicate, and one whose elements all do not satisfy the predicate.

  _.partition = function(obj, predicate, context) {

    predicate = cb(predicate, context);

    var pass = [], fail = [];

    _.each(obj, function(value, key, obj) {

      (predicate(value, key, obj) ? pass : fail).push(value);

    });

    return [pass, fail];

  };

  // Array Functions

  // ---------------

  // Get the first element of an array. Passing **n** will return the first N

  // values in the array. Aliased as `head` and `take`. The **guard** check

  // allows it to work with `_.map`.

  _.first = _.head = _.take = function(array, n, guard) {

    if (n == null || guard) return array[0];

    return _.initial(array, array.length - n);

  };

  // Returns everything but the last entry of the array. Especially useful on

  // the arguments object. Passing **n** will return all the values in

  // the array, excluding the last N.

  _.initial = function(array, n, guard) {

    return slice.call(array, 0, Math.max(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.

  _.last = function(array, n, guard) {

    if (n == null || guard) return array[array.length - 1];

    return _.rest(array, Math.max(0, array.length - n));

  };

  // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.

  // Especially useful on the arguments object. Passing an **n** will return

  // the rest N values in the array.

  _.rest = _.tail = _.drop = function(array, n, guard) {

    return slice.call(array, n == null || guard ? 1 : n);

  };

  // Trim out all falsy values from an array.

  _.compact = function(array) {

    return _.filter(array, _.identity);

  };

  // Internal implementation of a recursive `flatten` function.

  var flatten = function(input, shallow, strict, startIndex) {

    var output = [], idx = 0;

    for (var i = startIndex || 0, length = getLength(input); i < length; i++) {

      var value = input[i];

      if (isArrayLike(value) && (_.isArray(value) || _.isArguments(value))) {

        //flatten current level of array or arguments object

        if (!shallow) value = flatten(value, shallow, strict);

        var j = 0, len = value.length;

        output.length += len;

        while (j < len) {

          output[idx++] = value[j++];

        }

      } else if (!strict) {

        output[idx++] = value;

      }

    }

    return output;

  };

  // Flatten out an array, either recursively (by default), or just one level.

  _.flatten = function(array, shallow) {

    return flatten(array, shallow, false);

  };

  // 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, iteratee, context) {

    if (!_.isBoolean(isSorted)) {

      context = iteratee;

      iteratee = isSorted;

      isSorted = false;

    }

    if (iteratee != null) iteratee = cb(iteratee, context);

    var result = [];

    var seen = [];

    for (var i = 0, length = getLength(array); i < length; i++) {

      var value = array[i],

          computed = iteratee ? iteratee(value, i, array) : value;

      if (isSorted) {

        if (!i || seen !== computed) result.push(value);

        seen = computed;

      } else if (iteratee) {

        if (!_.contains(seen, computed)) {

          seen.push(computed);

          result.push(value);

        }

      } else if (!_.contains(result, value)) {

        result.push(value);

      }

    }

    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, true));

  };

  // Produce an array that contains every item shared between all the

  // passed-in arrays.

  _.intersection = function(array) {

    var result = [];

    var argsLength = arguments.length;

    for (var i = 0, length = getLength(array); i < length; i++) {

      var item = array[i];

      if (_.contains(result, item)) continue;

      for (var j = 1; j < argsLength; j++) {

        if (!_.contains(arguments[j], item)) break;

      }

      if (j === argsLength) result.push(item);

    }

    return result;

  };

  // Take the difference between one array and a number of other arrays.

  // Only the elements present in just the first array will remain.

  _.difference = function(array) {

    var rest = flatten(arguments, true, true, 1);

    return _.filter(array, function(value){

      return !_.contains(rest, value);

    });

  };

  // Zip together multiple lists into a single array -- elements that share

  // an index go together.

  _.zip = function() {

    return _.unzip(arguments);

  };

  // Complement of _.zip. Unzip accepts an array of arrays and groups

  // each array's elements on shared indices

  _.unzip = function(array) {

    var length = array && _.max(array, getLength).length || 0;

    var result = Array(length);

    for (var index = 0; index < length; index++) {

      result[index] = _.pluck(array, index);

    }

    return result;

  };

  // Converts lists into objects. Pass either a single array of `[key, value]`

  // pairs, or two parallel arrays of the same length -- one of keys, and one of

  // the corresponding values.

  _.object = function(list, values) {

    var result = {};

    for (var i = 0, length = getLength(list); i < length; i++) {

      if (values) {

        result[list[i]] = values[i];

      } else {

        result[list[i][0]] = list[i][1];

      }

    }

    return result;

  };

  // Generator function to create the findIndex and findLastIndex functions

  function createPredicateIndexFinder(dir) {

    return function(array, predicate, context) {

      predicate = cb(predicate, context);

      var length = getLength(array);

      var index = dir > 0 ? 0 : length - 1;

      for (; index >= 0 && index < length; index += dir) {

        if (predicate(array[index], index, array)) return index;

      }

      return -1;

    };

  }

  // Returns the first index on an array-like that passes a predicate test

  _.findIndex = createPredicateIndexFinder(1);

  _.findLastIndex = createPredicateIndexFinder(-1);

  // Use a comparator function to figure out the smallest index at which

  // an object should be inserted so as to maintain order. Uses binary search.

  _.sortedIndex = function(array, obj, iteratee, context) {

    iteratee = cb(iteratee, context, 1);

    var value = iteratee(obj);

    var low = 0, high = getLength(array);

    while (low < high) {

      var mid = Math.floor((low + high) / 2);

      if (iteratee(array[mid]) < value) low = mid + 1; else high = mid;

    }

    return low;

  };

  // Generator function to create the indexOf and lastIndexOf functions

  function createIndexFinder(dir, predicateFind, sortedIndex) {

    return function(array, item, idx) {

      var i = 0, length = getLength(array);

      if (typeof idx == 'number') {

        if (dir > 0) {

            i = idx >= 0 ? idx : Math.max(idx + length, i);

        } else {

            length = idx >= 0 ? Math.min(idx + 1, length) : idx + length + 1;

        }

      } else if (sortedIndex && idx && length) {

        idx = sortedIndex(array, item);

        return array[idx] === item ? idx : -1;

      }

      if (item !== item) {

        idx = predicateFind(slice.call(array, i, length), _.isNaN);

        return idx >= 0 ? idx + i : -1;

      }

      for (idx = dir > 0 ? i : length - 1; idx >= 0 && idx < length; idx += dir) {

        if (array[idx] === item) return idx;

      }

      return -1;

    };

  }

  // Return the position of the first occurrence of an item in an array,

  // or -1 if the item is not included in the array.

  // If the array is large and already in sort order, pass `true`

  // for **isSorted** to use binary search.

  _.indexOf = createIndexFinder(1, _.findIndex, _.sortedIndex);

  _.lastIndexOf = createIndexFinder(-1, _.findLastIndex);

  // 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 (stop == null) {

      stop = start || 0;

      start = 0;

    }

    step = step || 1;

    var length = Math.max(Math.ceil((stop - start) / step), 0);

    var range = Array(length);

    for (var idx = 0; idx < length; idx++, start += step) {

      range[idx] = start;

    }

    return range;

  };

  // Function (ahem) Functions

  // ------------------

  // Determines whether to execute a function as a constructor

  // or a normal function with the provided arguments

  var executeBound = function(sourceFunc, boundFunc, context, callingContext, args) {

    if (!(callingContext instanceof boundFunc)) return sourceFunc.apply(context, args);

    var self = baseCreate(sourceFunc.prototype);

    var result = sourceFunc.apply(self, args);

    if (_.isObject(result)) return result;

    return self;

  };

  // Create a function bound to a given object (assigning `this`, and arguments,

  // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if

  // available.

  _.bind = function(func, context) {

    if (nativeBind && func.bind === nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));

    if (!_.isFunction(func)) throw new TypeError('Bind must be called on a function');

    var args = slice.call(arguments, 2);

    var bound = function() {

      return executeBound(func, bound, context, this, args.concat(slice.call(arguments)));

    };

    return bound;

  };

  // Partially apply a function by creating a version that has had some of its

  // arguments pre-filled, without changing its dynamic `this` context. _ acts

  // as a placeholder, allowing any combination of arguments to be pre-filled.

  _.partial = function(func) {

    var boundArgs = slice.call(arguments, 1);

    var bound = function() {

      var position = 0, length = boundArgs.length;

      var args = Array(length);

      for (var i = 0; i < length; i++) {

        args[i] = boundArgs[i] === _ ? arguments[position++] : boundArgs[i];

      }

      while (position < arguments.length) args.push(arguments[position++]);

      return executeBound(func, bound, this, this, args);

    };

    return bound;

  };

  // Bind a number of an object's methods to that object. Remaining arguments

  // are the method names to be bound. Useful for ensuring that all callbacks

  // defined on an object belong to it.

  _.bindAll = function(obj) {

    var i, length = arguments.length, key;

    if (length <= 1) throw new Error('bindAll must be passed function names');

    for (i = 1; i < length; i++) {

      key = arguments[i];

      obj[key] = _.bind(obj[key], obj);

    }

    return obj;

  };

  // Memoize an expensive function by storing its results.

  _.memoize = function(func, hasher) {

    var memoize = function(key) {

      var cache = memoize.cache;

      var address = '' + (hasher ? hasher.apply(this, arguments) : key);

      if (!_.has(cache, address)) cache[address] = func.apply(this, arguments);

      return cache[address];

    };

    memoize.cache = {};

    return memoize;

  };

  // 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(null, args);

    }, wait);

  };

  // Defers a function, scheduling it to run after the current call stack has

  // cleared.

  _.defer = _.partial(_.delay, _, 1);

  // Returns a function, that, when invoked, will only be triggered at most once

  // during a given window of time. Normally, the throttled function will run

  // as much as it can, without ever going more than once per `wait` duration;

  // but if you'd like to disable the execution on the leading edge, pass

  // `{leading: false}`. To disable execution on the trailing edge, ditto.

  _.throttle = function(func, wait, options) {

    var context, args, result;

    var timeout = null;

    var previous = 0;

    if (!options) options = {};

    var later = function() {

      previous = options.leading === false ? 0 : _.now();

      timeout = null;

      result = func.apply(context, args);

      if (!timeout) context = args = null;

    };

    return function() {

      var now = _.now();

      if (!previous && options.leading === false) previous = now;

      var remaining = wait - (now - previous);

      context = this;

      args = arguments;

      if (remaining <= 0 || remaining > wait) {

        if (timeout) {

          clearTimeout(timeout);

          timeout = null;

        }

        previous = now;

        result = func.apply(context, args);

        if (!timeout) context = args = null;

      } else if (!timeout && options.trailing !== false) {

        timeout = setTimeout(later, remaining);

      }

    };

  };

  // 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. If `immediate` is passed, trigger the function on the

  // leading edge, instead of the trailing.

  _.debounce = function(func, wait, immediate) {

    var timeout, args, context, timestamp, result;

    var later = function() {

      var last = _.now() - timestamp;

      if (last < wait && last >= 0) {

        timeout = setTimeout(later, wait - last);

      } else {

        timeout = null;

        if (!immediate) {

          result = func.apply(context, args);

          if (!timeout) context = args = null;

        }

      }

    };

    return function() {

      context = this;

      args = arguments;

      timestamp = _.now();

      var callNow = immediate && !timeout;

      if (!timeout) timeout = setTimeout(later, wait);

      if (callNow) {

        result = func.apply(context, args);

        context = args = null;

      }

    };

  };

  // 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 _.partial(wrapper, func);

  };

  // Returns a negated version of the passed-in predicate.

  _.negate = function(predicate) {

    return function() {

      return !predicate.apply(this, arguments);

    };

  };

  // 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 args = arguments;

    var start = args.length - 1;

    return function() {

      var i = start;

      var result = args[start].apply(this, arguments);

      while (i--) result = args[i].call(this, result);