/front/node_modules/lodash/dist/lodash.js

/**
 * @license
 * Lo-Dash 1.0.2 (Custom Build) <http://lodash.com/>
 * Build: `lodash modern -o ./dist/lodash.js`
 * Copyright 2012-2013 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.4.4 <http://underscorejs.org/>
 * Copyright 2009-2013 Jeremy Ashkenas, DocumentCloud Inc.
 * Available under MIT license <http://lodash.com/license>
 */
;(function(window, undefined) {

  /** Detect free variable `exports` */
  var freeExports = typeof exports == 'object' && exports;

  /** Detect free variable `module` */
  var freeModule = typeof module == 'object' && module && module.exports == freeExports && module;

  /** Detect free variable `global` and use it as `window` */
  var freeGlobal = typeof global == 'object' && global;
  if (freeGlobal.global === freeGlobal) {
    window = freeGlobal;
  }

  /** Used for array and object method references */
  var arrayRef = [],
      objectRef = {};

  /** Used to generate unique IDs */
  var idCounter = 0;

  /** Used internally to indicate various things */
  var indicatorObject = objectRef;

  /** Used by `cachedContains` as the default size when optimizations are enabled for large arrays */
  var largeArraySize = 30;

  /** Used to restore the original `_` reference in `noConflict` */
  var oldDash = window._;

  /** Used to match HTML entities */
  var reEscapedHtml = /&(?:amp|lt|gt|quot|#39);/g;

  /** Used to match empty string literals in compiled template source */
  var reEmptyStringLeading = /\b__p \+= '';/g,
      reEmptyStringMiddle = /\b(__p \+=) '' \+/g,
      reEmptyStringTrailing = /(__e\(.*?\)|\b__t\)) \+\n'';/g;

  /** Used to match regexp flags from their coerced string values */
  var reFlags = /\w*$/;

  /** Used to detect if a method is native */
  var reNative = RegExp('^' +
    (objectRef.valueOf + '')
      .replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
      .replace(/valueOf|for [^\]]+/g, '.+?') + '$'
  );

  /**
   * Used to match ES6 template delimiters
   * http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.8.6
   */
  var reEsTemplate = /\$\{([^\\}]*(?:\\.[^\\}]*)*)\}/g;

  /** Used to match "interpolate" template delimiters */
  var reInterpolate = /<%=([\s\S]+?)%>/g;

  /** Used to ensure capturing order of template delimiters */
  var reNoMatch = /($^)/;

  /** Used to match HTML characters */
  var reUnescapedHtml = /[&<>"']/g;

  /** Used to match unescaped characters in compiled string literals */
  var reUnescapedString = /['\n\r\t\u2028\u2029\\]/g;

  /** Used to make template sourceURLs easier to identify */
  var templateCounter = 0;

  /** Native method shortcuts */
  var ceil = Math.ceil,
      concat = arrayRef.concat,
      floor = Math.floor,
      getPrototypeOf = reNative.test(getPrototypeOf = Object.getPrototypeOf) && getPrototypeOf,
      hasOwnProperty = objectRef.hasOwnProperty,
      push = arrayRef.push,
      toString = objectRef.toString;

  /* Native method shortcuts for methods with the same name as other `lodash` methods */
  var nativeBind = reNative.test(nativeBind = slice.bind) && nativeBind,
      nativeIsArray = reNative.test(nativeIsArray = Array.isArray) && nativeIsArray,
      nativeIsFinite = window.isFinite,
      nativeIsNaN = window.isNaN,
      nativeKeys = reNative.test(nativeKeys = Object.keys) && nativeKeys,
      nativeMax = Math.max,
      nativeMin = Math.min,
      nativeRandom = Math.random;

  /** `Object#toString` result shortcuts */
  var argsClass = '[object Arguments]',
      arrayClass = '[object Array]',
      boolClass = '[object Boolean]',
      dateClass = '[object Date]',
      funcClass = '[object Function]',
      numberClass = '[object Number]',
      objectClass = '[object Object]',
      regexpClass = '[object RegExp]',
      stringClass = '[object String]';

  /** Detect various environments */
  var isIeOpera = !!window.attachEvent,
      isV8 = nativeBind && !/\n|true/.test(nativeBind + isIeOpera);

  /* Detect if `Function#bind` exists and is inferred to be fast (all but V8) */
  var isBindFast = nativeBind && !isV8;

  /* Detect if `Object.keys` exists and is inferred to be fast (IE, Opera, V8) */
  var isKeysFast = nativeKeys && (isIeOpera || isV8);

  /** Used to identify object classifications that `_.clone` supports */
  var cloneableClasses = {};
  cloneableClasses[funcClass] = false;
  cloneableClasses[argsClass] = cloneableClasses[arrayClass] =
  cloneableClasses[boolClass] = cloneableClasses[dateClass] =
  cloneableClasses[numberClass] = cloneableClasses[objectClass] =
  cloneableClasses[regexpClass] = cloneableClasses[stringClass] = true;

  /** Used to lookup a built-in constructor by [[Class]] */
  var ctorByClass = {};
  ctorByClass[arrayClass] = Array;
  ctorByClass[boolClass] = Boolean;
  ctorByClass[dateClass] = Date;
  ctorByClass[objectClass] = Object;
  ctorByClass[numberClass] = Number;
  ctorByClass[regexpClass] = RegExp;
  ctorByClass[stringClass] = String;

  /** Used to determine if values are of the language type Object */
  var objectTypes = {
    'boolean': false,
    'function': true,
    'object': true,
    'number': false,
    'string': false,
    'undefined': false
  };

  /** Used to escape characters for inclusion in compiled string literals */
  var stringEscapes = {
    '\\': '\\',
    "'": "'",
    '\n': 'n',
    '\r': 'r',
    '\t': 't',
    '\u2028': 'u2028',
    '\u2029': 'u2029'
  };

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a `lodash` object, that wraps the given `value`, to enable method
   * chaining.
   *
   * In addition to Lo-Dash methods, wrappers also have the following `Array` methods:
   * `concat`, `join`, `pop`, `push`, `reverse`, `shift`, `slice`, `sort`, `splice`,
   * and `unshift`
   *
   * The chainable wrapper functions are:
   * `after`, `assign`, `bind`, `bindAll`, `bindKey`, `chain`, `compact`, `compose`,
   * `concat`, `countBy`, `debounce`, `defaults`, `defer`, `delay`, `difference`,
   * `filter`, `flatten`, `forEach`, `forIn`, `forOwn`, `functions`, `groupBy`,
   * `initial`, `intersection`, `invert`, `invoke`, `keys`, `map`, `max`, `memoize`,
   * `merge`, `min`, `object`, `omit`, `once`, `pairs`, `partial`, `partialRight`,
   * `pick`, `pluck`, `push`, `range`, `reject`, `rest`, `reverse`, `shuffle`,
   * `slice`, `sort`, `sortBy`, `splice`, `tap`, `throttle`, `times`, `toArray`,
   * `union`, `uniq`, `unshift`, `values`, `where`, `without`, `wrap`, and `zip`
   *
   * The non-chainable wrapper functions are:
   * `clone`, `cloneDeep`, `contains`, `escape`, `every`, `find`, `has`, `identity`,
   * `indexOf`, `isArguments`, `isArray`, `isBoolean`, `isDate`, `isElement`, `isEmpty`,
   * `isEqual`, `isFinite`, `isFunction`, `isNaN`, `isNull`, `isNumber`, `isObject`,
   * `isPlainObject`, `isRegExp`, `isString`, `isUndefined`, `join`, `lastIndexOf`,
   * `mixin`, `noConflict`, `pop`, `random`, `reduce`, `reduceRight`, `result`,
   * `shift`, `size`, `some`, `sortedIndex`, `template`, `unescape`, and `uniqueId`
   *
   * The wrapper functions `first` and `last` return wrapped values when `n` is
   * passed, otherwise they return unwrapped values.
   *
   * @name _
   * @constructor
   * @category Chaining
   * @param {Mixed} value The value to wrap in a `lodash` instance.
   * @returns {Object} Returns a `lodash` instance.
   */
  function lodash(value) {
    // exit early if already wrapped, even if wrapped by a different `lodash` constructor
    if (value && typeof value == 'object' && value.__wrapped__) {
      return value;
    }
    // allow invoking `lodash` without the `new` operator
    if (!(this instanceof lodash)) {
      return new lodash(value);
    }
    this.__wrapped__ = value;
  }

  /**
   * By default, the template delimiters used by Lo-Dash are similar to those in
   * embedded Ruby (ERB). Change the following template settings to use alternative
   * delimiters.
   *
   * @static
   * @memberOf _
   * @type Object
   */
  lodash.templateSettings = {

    /**
     * Used to detect `data` property values to be HTML-escaped.
     *
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'escape': /<%-([\s\S]+?)%>/g,

    /**
     * Used to detect code to be evaluated.
     *
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'evaluate': /<%([\s\S]+?)%>/g,

    /**
     * Used to detect `data` property values to inject.
     *
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'interpolate': reInterpolate,

    /**
     * Used to reference the data object in the template text.
     *
     * @memberOf _.templateSettings
     * @type String
     */
    'variable': '',

    /**
     * Used to import variables into the compiled template.
     *
     * @memberOf _.templateSettings
     * @type Object
     */
    'imports': {

      /**
       * A reference to the `lodash` function.
       *
       * @memberOf _.templateSettings.imports
       * @type Function
       */
      '_': lodash
    }
  };

  /*--------------------------------------------------------------------------*/

  /**
   * The template used to create iterator functions.
   *
   * @private
   * @param {Obect} data The data object used to populate the text.
   * @returns {String} Returns the interpolated text.
   */
  var iteratorTemplate = function(obj) {
    
    var __p = 'var index, iterable = ' +
    (obj.firstArg ) +
    ', result = iterable;\nif (!iterable) return result;\n' +
    (obj.top ) +
    ';\n';
     if (obj.arrays) {
    __p += 'var length = iterable.length; index = -1;\nif (' +
    (obj.arrays ) +
    ') {\n  while (++index < length) {\n    ' +
    (obj.loop ) +
    '\n  }\n}\nelse {  ';
     } ;
    
     if (obj.isKeysFast && obj.useHas) {
    __p += '\n  var ownIndex = -1,\n      ownProps = objectTypes[typeof iterable] ? nativeKeys(iterable) : [],\n      length = ownProps.length;\n\n  while (++ownIndex < length) {\n    index = ownProps[ownIndex];\n    ' +
    (obj.loop ) +
    '\n  }  ';
     } else {
    __p += '\n  for (index in iterable) {';
        if (obj.useHas) {
    __p += '\n    if (';
          if (obj.useHas) {
    __p += 'hasOwnProperty.call(iterable, index)';
     }    ;
    __p += ') {    ';
     } ;
    __p += 
    (obj.loop ) +
    ';    ';
     if (obj.useHas) {
    __p += '\n    }';
     } ;
    __p += '\n  }  ';
     } ;
    
     if (obj.arrays) {
    __p += '\n}';
     } ;
    __p += 
    (obj.bottom ) +
    ';\nreturn result';
    
    
    return __p
  };

  /** Reusable iterator options for `assign` and `defaults` */
  var defaultsIteratorOptions = {
    'args': 'object, source, guard',
    'top':
      'var args = arguments,\n' +
      '    argsIndex = 0,\n' +
      "    argsLength = typeof guard == 'number' ? 2 : args.length;\n" +
      'while (++argsIndex < argsLength) {\n' +
      '  iterable = args[argsIndex];\n' +
      '  if (iterable && objectTypes[typeof iterable]) {',
    'loop': "if (typeof result[index] == 'undefined') result[index] = iterable[index]",
    'bottom': '  }\n}'
  };

  /** Reusable iterator options shared by `each`, `forIn`, and `forOwn` */
  var eachIteratorOptions = {
    'args': 'collection, callback, thisArg',
    'top': "callback = callback && typeof thisArg == 'undefined' ? callback : createCallback(callback, thisArg)",
    'arrays': "typeof length == 'number'",
    'loop': 'if (callback(iterable[index], index, collection) === false) return result'
  };

  /** Reusable iterator options for `forIn` and `forOwn` */
  var forOwnIteratorOptions = {
    'top': 'if (!objectTypes[typeof iterable]) return result;\n' + eachIteratorOptions.top,
    'arrays': false
  };

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a function optimized to search large arrays for a given `value`,
   * starting at `fromIndex`, using strict equality for comparisons, i.e. `===`.
   *
   * @private
   * @param {Array} array The array to search.
   * @param {Mixed} value The value to search for.
   * @param {Number} [fromIndex=0] The index to search from.
   * @param {Number} [largeSize=30] The length at which an array is considered large.
   * @returns {Boolean} Returns `true`, if `value` is found, else `false`.
   */
  function cachedContains(array, fromIndex, largeSize) {
    fromIndex || (fromIndex = 0);

    var length = array.length,
        isLarge = (length - fromIndex) >= (largeSize || largeArraySize);

    if (isLarge) {
      var cache = {},
          index = fromIndex - 1;

      while (++index < length) {
        // manually coerce `value` to a string because `hasOwnProperty`, in some
        // older versions of Firefox, coerces objects incorrectly
        var key = array[index] + '';
        (hasOwnProperty.call(cache, key) ? cache[key] : (cache[key] = [])).push(array[index]);
      }
    }
    return function(value) {
      if (isLarge) {
        var key = value + '';
        return hasOwnProperty.call(cache, key) && indexOf(cache[key], value) > -1;
      }
      return indexOf(array, value, fromIndex) > -1;
    }
  }

  /**
   * Used by `_.max` and `_.min` as the default `callback` when a given
   * `collection` is a string value.
   *
   * @private
   * @param {String} value The character to inspect.
   * @returns {Number} Returns the code unit of given character.
   */
  function charAtCallback(value) {
    return value.charCodeAt(0);
  }

  /**
   * Used by `sortBy` to compare transformed `collection` values, stable sorting
   * them in ascending order.
   *
   * @private
   * @param {Object} a The object to compare to `b`.
   * @param {Object} b The object to compare to `a`.
   * @returns {Number} Returns the sort order indicator of `1` or `-1`.
   */
  function compareAscending(a, b) {
    var ai = a.index,
        bi = b.index;

    a = a.criteria;
    b = b.criteria;

    // ensure a stable sort in V8 and other engines
    // http://code.google.com/p/v8/issues/detail?id=90
    if (a !== b) {
      if (a > b || typeof a == 'undefined') {
        return 1;
      }
      if (a < b || typeof b == 'undefined') {
        return -1;
      }
    }
    return ai < bi ? -1 : 1;
  }

  /**
   * Creates a function that, when called, invokes `func` with the `this` binding
   * of `thisArg` and prepends any `partialArgs` to the arguments passed to the
   * bound function.
   *
   * @private
   * @param {Function|String} func The function to bind or the method name.
   * @param {Mixed} [thisArg] The `this` binding of `func`.
   * @param {Array} partialArgs An array of arguments to be partially applied.
   * @param {Object} [rightIndicator] Used to indicate partially applying arguments from the right.
   * @returns {Function} Returns the new bound function.
   */
  function createBound(func, thisArg, partialArgs, rightIndicator) {
    var isFunc = isFunction(func),
        isPartial = !partialArgs,
        key = thisArg;

    // juggle arguments
    if (isPartial) {
      partialArgs = thisArg;
    }
    if (!isFunc) {
      thisArg = func;
    }

    function bound() {
      // `Function#bind` spec
      // http://es5.github.com/#x15.3.4.5
      var args = arguments,
          thisBinding = isPartial ? this : thisArg;

      if (!isFunc) {
        func = thisArg[key];
      }
      if (partialArgs.length) {
        args = args.length
          ? (args = slice(args), rightIndicator ? args.concat(partialArgs) : partialArgs.concat(args))
          : partialArgs;
      }
      if (this instanceof bound) {
        // ensure `new bound` is an instance of `bound` and `func`
        noop.prototype = func.prototype;
        thisBinding = new noop;
        noop.prototype = null;

        // mimic the constructor's `return` behavior
        // http://es5.github.com/#x13.2.2
        var result = func.apply(thisBinding, args);
        return isObject(result) ? result : thisBinding;
      }
      return func.apply(thisBinding, args);
    }
    return bound;
  }

  /**
   * Produces a callback bound to an optional `thisArg`. If `func` is a property
   * name, the created callback will return the property value for a given element.
   * If `func` is an object, the created callback will return `true` for elements
   * that contain the equivalent object properties, otherwise it will return `false`.
   *
   * @private
   * @param {Mixed} [func=identity] The value to convert to a callback.
   * @param {Mixed} [thisArg] The `this` binding of the created callback.
   * @param {Number} [argCount=3] The number of arguments the callback accepts.
   * @returns {Function} Returns a callback function.
   */
  function createCallback(func, thisArg, argCount) {
    if (func == null) {
      return identity;
    }
    var type = typeof func;
    if (type != 'function') {
      if (type != 'object') {
        return function(object) {
          return object[func];
        };
      }
      var props = keys(func);
      return function(object) {
        var length = props.length,
            result = false;
        while (length--) {
          if (!(result = isEqual(object[props[length]], func[props[length]], indicatorObject))) {
            break;
          }
        }
        return result;
      };
    }
    if (typeof thisArg != 'undefined') {
      if (argCount === 1) {
        return function(value) {
          return func.call(thisArg, value);
        };
      }
      if (argCount === 2) {
        return function(a, b) {
          return func.call(thisArg, a, b);
        };
      }
      if (argCount === 4) {
        return function(accumulator, value, index, object) {
          return func.call(thisArg, accumulator, value, index, object);
        };
      }
      return function(value, index, object) {
        return func.call(thisArg, value, index, object);
      };
    }
    return func;
  }

  /**
   * Creates compiled iteration functions.
   *
   * @private
   * @param {Object} [options1, options2, ...] The compile options object(s).
   *  arrays - A string of code to determine if the iterable is an array or array-like.
   *  useHas - A boolean to specify using `hasOwnProperty` checks in the object loop.
   *  args - A string of comma separated arguments the iteration function will accept.
   *  top - A string of code to execute before the iteration branches.
   *  loop - A string of code to execute in the object loop.
   *  bottom - A string of code to execute after the iteration branches.
   *
   * @returns {Function} Returns the compiled function.
   */
  function createIterator() {
    var data = {
      // support properties
      'isKeysFast': isKeysFast,

      // iterator options
      'arrays': 'isArray(iterable)',
      'bottom': '',
      'loop': '',
      'top': '',
      'useHas': true
    };

    // merge options into a template data object
    for (var object, index = 0; object = arguments[index]; index++) {
      for (var key in object) {
        data[key] = object[key];
      }
    }
    var args = data.args;
    data.firstArg = /^[^,]+/.exec(args)[0];

    // create the function factory
    var factory = Function(
        'createCallback, hasOwnProperty, isArguments, isArray, isString, ' +
        'objectTypes, nativeKeys',
      'return function(' + args + ') {\n' + iteratorTemplate(data) + '\n}'
    );
    // return the compiled function
    return factory(
      createCallback, hasOwnProperty, isArguments, isArray, isString,
      objectTypes, nativeKeys
    );
  }

  /**
   * A function compiled to iterate `arguments` objects, arrays, objects, and
   * strings consistenly across environments, executing the `callback` for each
   * element in the `collection`. The `callback` is bound to `thisArg` and invoked
   * with three arguments; (value, index|key, collection). Callbacks may exit
   * iteration early by explicitly returning `false`.
   *
   * @private
   * @type Function
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Array|Object|String} Returns `collection`.
   */
  var each = createIterator(eachIteratorOptions);

  /**
   * Used by `template` to escape characters for inclusion in compiled
   * string literals.
   *
   * @private
   * @param {String} match The matched character to escape.
   * @returns {String} Returns the escaped character.
   */
  function escapeStringChar(match) {
    return '\\' + stringEscapes[match];
  }

  /**
   * Used by `escape` to convert characters to HTML entities.
   *
   * @private
   * @param {String} match The matched character to escape.
   * @returns {String} Returns the escaped character.
   */
  function escapeHtmlChar(match) {
    return htmlEscapes[match];
  }

  /**
   * Checks if `value` is a DOM node in IE < 9.
   *
   * @private
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a DOM node, else `false`.
   */
  function isNode(value) {
    // IE < 9 presents DOM nodes as `Object` objects except they have `toString`
    // methods that are `typeof` "string" and still can coerce nodes to strings
    return typeof value.toString != 'function' && typeof (value + '') == 'string';
  }

  /**
   * A no-operation function.
   *
   * @private
   */
  function noop() {
    // no operation performed
  }

  /**
   * Slices the `collection` from the `start` index up to, but not including,
   * the `end` index.
   *
   * Note: This function is used, instead of `Array#slice`, to support node lists
   * in IE < 9 and to ensure dense arrays are returned.
   *
   * @private
   * @param {Array|Object|String} collection The collection to slice.
   * @param {Number} start The start index.
   * @param {Number} end The end index.
   * @returns {Array} Returns the new array.
   */
  function slice(array, start, end) {
    start || (start = 0);
    if (typeof end == 'undefined') {
      end = array ? array.length : 0;
    }
    var index = -1,
        length = end - start || 0,
        result = Array(length < 0 ? 0 : length);

    while (++index < length) {
      result[index] = array[start + index];
    }
    return result;
  }

  /**
   * Used by `unescape` to convert HTML entities to characters.
   *
   * @private
   * @param {String} match The matched character to unescape.
   * @returns {String} Returns the unescaped character.
   */
  function unescapeHtmlChar(match) {
    return htmlUnescapes[match];
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Checks if `value` is an `arguments` object.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is an `arguments` object, else `false`.
   * @example
   *
   * (function() { return _.isArguments(arguments); })(1, 2, 3);
   * // => true
   *
   * _.isArguments([1, 2, 3]);
   * // => false
   */
  function isArguments(value) {
    return toString.call(value) == argsClass;
  }

  /**
   * Iterates over `object`'s own and inherited enumerable properties, executing
   * the `callback` for each property. The `callback` is bound to `thisArg` and
   * invoked with three arguments; (value, key, object). Callbacks may exit iteration
   * early by explicitly returning `false`.
   *
   * @static
   * @memberOf _
   * @type Function
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Object} Returns `object`.
   * @example
   *
   * function Dog(name) {
   *   this.name = name;
   * }
   *
   * Dog.prototype.bark = function() {
   *   alert('Woof, woof!');
   * };
   *
   * _.forIn(new Dog('Dagny'), function(value, key) {
   *   alert(key);
   * });
   * // => alerts 'name' and 'bark' (order is not guaranteed)
   */
  var forIn = createIterator(eachIteratorOptions, forOwnIteratorOptions, {
    'useHas': false
  });

  /**
   * Iterates over an object's own enumerable properties, executing the `callback`
   * for each property. The `callback` is bound to `thisArg` and invoked with three
   * arguments; (value, key, object). Callbacks may exit iteration early by explicitly
   * returning `false`.
   *
   * @static
   * @memberOf _
   * @type Function
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Object} Returns `object`.
   * @example
   *
   * _.forOwn({ '0': 'zero', '1': 'one', 'length': 2 }, function(num, key) {
   *   alert(key);
   * });
   * // => alerts '0', '1', and 'length' (order is not guaranteed)
   */
  var forOwn = createIterator(eachIteratorOptions, forOwnIteratorOptions);

  /**
   * Checks if `value` is an array.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is an array, else `false`.
   * @example
   *
   * (function() { return _.isArray(arguments); })();
   * // => false
   *
   * _.isArray([1, 2, 3]);
   * // => true
   */
  var isArray = nativeIsArray || function(value) {
    // `instanceof` may cause a memory leak in IE 7 if `value` is a host object
    // http://ajaxian.com/archives/working-aroung-the-instanceof-memory-leak
    return value instanceof Array || toString.call(value) == arrayClass;
  };

  /**
   * Creates an array composed of the own enumerable property names of `object`.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names.
   * @example
   *
   * _.keys({ 'one': 1, 'two': 2, 'three': 3 });
   * // => ['one', 'two', 'three'] (order is not guaranteed)
   */
  var keys = !nativeKeys ? shimKeys : function(object) {
    if (!isObject(object)) {
      return [];
    }
    return nativeKeys(object);
  };

  /**
   * A fallback implementation of `isPlainObject` that checks if a given `value`
   * is an object created by the `Object` constructor, assuming objects created
   * by the `Object` constructor have no inherited enumerable properties and that
   * there are no `Object.prototype` extensions.
   *
   * @private
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if `value` is a plain object, else `false`.
   */
  function shimIsPlainObject(value) {
    // avoid non-objects and false positives for `arguments` objects
    var result = false;
    if (!(value && typeof value == 'object') || isArguments(value)) {
      return result;
    }
    // check that the constructor is `Object` (i.e. `Object instanceof Object`)
    var ctor = value.constructor;
    if ((!isFunction(ctor)) || ctor instanceof ctor) {
      // In most environments an object's own properties are iterated before
      // its inherited properties. If the last iterated property is an object's
      // own property then there are no inherited enumerable properties.
      forIn(value, function(value, key) {
        result = key;
      });
      return result === false || hasOwnProperty.call(value, result);
    }
    return result;
  }

  /**
   * A fallback implementation of `Object.keys` that produces an array of the
   * given object's own enumerable property names.
   *
   * @private
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names.
   */
  function shimKeys(object) {
    var result = [];
    forOwn(object, function(value, key) {
      result.push(key);
    });
    return result;
  }

  /**
   * Used to convert characters to HTML entities:
   *
   * Though the `>` character is escaped for symmetry, characters like `>` and `/`
   * don't require escaping in HTML and have no special meaning unless they're part
   * of a tag or an unquoted attribute value.
   * http://mathiasbynens.be/notes/ambiguous-ampersands (under "semi-related fun fact")
   */
  var htmlEscapes = {
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    '"': '&quot;',
    "'": '&#39;'
  };

  /** Used to convert HTML entities to characters */
  var htmlUnescapes = invert(htmlEscapes);

  /*--------------------------------------------------------------------------*/

  /**
   * Assigns own enumerable properties of source object(s) to the destination
   * object. Subsequent sources will overwrite propery assignments of previous
   * sources. If a `callback` function is passed, it will be executed to produce
   * the assigned values. The `callback` is bound to `thisArg` and invoked with
   * two arguments; (objectValue, sourceValue).
   *
   * @static
   * @memberOf _
   * @type Function
   * @alias extend
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [source1, source2, ...] The source objects.
   * @param {Function} [callback] The function to customize assigning values.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Object} Returns the destination object.
   * @example
   *
   * _.assign({ 'name': 'moe' }, { 'age': 40 });
   * // => { 'name': 'moe', 'age': 40 }
   *
   * var defaults = _.partialRight(_.assign, function(a, b) {
   *   return typeof a == 'undefined' ? b : a;
   * });
   *
   * var food = { 'name': 'apple' };
   * defaults(food, { 'name': 'banana', 'type': 'fruit' });
   * // => { 'name': 'apple', 'type': 'fruit' }
   */
  var assign = createIterator(defaultsIteratorOptions, {
    'top':
      defaultsIteratorOptions.top.replace(';',
        ';\n' +
        "if (argsLength > 3 && typeof args[argsLength - 2] == 'function') {\n" +
        '  var callback = createCallback(args[--argsLength - 1], args[argsLength--], 2);\n' +
        "} else if (argsLength > 2 && typeof args[argsLength - 1] == 'function') {\n" +
        '  callback = args[--argsLength];\n' +
        '}'
      ),
    'loop': 'result[index] = callback ? callback(result[index], iterable[index]) : iterable[index]'
  });

  /**
   * Creates a clone of `value`. If `deep` is `true`, nested objects will also
   * be cloned, otherwise they will be assigned by reference. If a `callback`
   * function is passed, it will be executed to produce the cloned values. If
   * `callback` returns `undefined`, cloning will be handled by the method instead.
   * The `callback` is bound to `thisArg` and invoked with one argument; (value).
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to clone.
   * @param {Boolean} [deep=false] A flag to indicate a deep clone.
   * @param {Function} [callback] The function to customize cloning values.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @param- {Array} [stackA=[]] Internally used to track traversed source objects.
   * @param- {Array} [stackB=[]] Internally used to associate clones with source counterparts.
   * @returns {Mixed} Returns the cloned `value`.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 }
   * ];
   *
   * var shallow = _.clone(stooges);
   * shallow[0] === stooges[0];
   * // => true
   *
   * var deep = _.clone(stooges, true);
   * deep[0] === stooges[0];
   * // => false
   *
   * _.mixin({
   *   'clone': _.partialRight(_.clone, function(value) {
   *     return _.isElement(value) ? value.cloneNode(false) : undefined;
   *   })
   * });
   *
   * var clone = _.clone(document.body);
   * clone.childNodes.length;
   * // => 0
   */
  function clone(value, deep, callback, thisArg, stackA, stackB) {
    var result = value;

    // allows working with "Collections" methods without using their `callback`
    // argument, `index|key`, for this method's `callback`
    if (typeof deep == 'function') {
      thisArg = callback;
      callback = deep;
      deep = false;
    }
    if (typeof callback == 'function') {
      callback = typeof thisArg == 'undefined' ? callback : createCallback(callback, thisArg, 1);
      result = callback(result);

      var done = typeof result != 'undefined';
      if (!done) {
        result = value;
      }
    }
    // inspect [[Class]]
    var isObj = isObject(result);
    if (isObj) {
      var className = toString.call(result);
      if (!cloneableClasses[className]) {
        return result;
      }
      var isArr = isArray(result);
    }
    // shallow clone
    if (!isObj || !deep) {
      return isObj && !done
        ? (isArr ? slice(result) : assign({}, result))
        : result;
    }
    var ctor = ctorByClass[className];
    switch (className) {
      case boolClass:
      case dateClass:
        return done ? result : new ctor(+result);

      case numberClass:
      case stringClass:
        return done ? result : new ctor(result);

      case regexpClass:
        return done ? result : ctor(result.source, reFlags.exec(result));
    }
    // check for circular references and return corresponding clone
    stackA || (stackA = []);
    stackB || (stackB = []);

    var length = stackA.length;
    while (length--) {
      if (stackA[length] == value) {
        return stackB[length];
      }
    }
    // init cloned object
    if (!done) {
      result = isArr ? ctor(result.length) : {};

      // add array properties assigned by `RegExp#exec`
      if (isArr) {
        if (hasOwnProperty.call(value, 'index')) {
          result.index = value.index;
        }
        if (hasOwnProperty.call(value, 'input')) {
          result.input = value.input;
        }
      }
    }
    // add the source value to the stack of traversed objects
    // and associate it with its clone
    stackA.push(value);
    stackB.push(result);

    // recursively populate clone (susceptible to call stack limits)
    (isArr ? forEach : forOwn)(done ? result : value, function(objValue, key) {
      result[key] = clone(objValue, deep, callback, undefined, stackA, stackB);
    });

    return result;
  }

  /**
   * Creates a deep clone of `value`. If a `callback` function is passed, it will
   * be executed to produce the cloned values. If `callback` returns the value it
   * was passed, cloning will be handled by the method instead. The `callback` is
   * bound to `thisArg` and invoked with one argument; (value).
   *
   * Note: This function is loosely based on the structured clone algorithm. Functions
   * and DOM nodes are **not** cloned. The enumerable properties of `arguments` objects and
   * objects created by constructors other than `Object` are cloned to plain `Object` objects.
   * See http://www.w3.org/TR/html5/infrastructure.html#internal-structured-cloning-algorithm.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to deep clone.
   * @param {Function} [callback] The function to customize cloning values.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Mixed} Returns the deep cloned `value`.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 }
   * ];
   *
   * var deep = _.cloneDeep(stooges);
   * deep[0] === stooges[0];
   * // => false
   *
   * var view = {
   *   'label': 'docs',
   *   'node': element
   * };
   *
   * var clone = _.cloneDeep(view, function(value) {
   *   return _.isElement(value) ? value.cloneNode(true) : value;
   * });
   *
   * clone.node == view.node;
   * // => false
   */
  function cloneDeep(value, callback, thisArg) {
    return clone(value, true, callback, thisArg);
  }

  /**
   * Assigns own enumerable properties of source object(s) to the destination
   * object for all destination properties that resolve to `undefined`. Once a
   * property is set, additional defaults of the same property will be ignored.
   *
   * @static
   * @memberOf _
   * @type Function
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [source1, source2, ...] The source objects.
   * @param- {Object} [guard] Internally used to allow working with `_.reduce`
   *  without using its callback's `key` and `object` arguments as sources.
   * @returns {Object} Returns the destination object.
   * @example
   *
   * var food = { 'name': 'apple' };
   * _.defaults(food, { 'name': 'banana', 'type': 'fruit' });
   * // => { 'name': 'apple', 'type': 'fruit' }
   */
  var defaults = createIterator(defaultsIteratorOptions);

  /**
   * Creates a sorted array of all enumerable properties, own and inherited,
   * of `object` that have function values.
   *
   * @static
   * @memberOf _
   * @alias methods
   * @category Objects
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names that have function values.
   * @example
   *
   * _.functions(_);
   * // => ['all', 'any', 'bind', 'bindAll', 'clone', 'compact', 'compose', ...]
   */
  function functions(object) {
    var result = [];
    forIn(object, function(value, key) {
      if (isFunction(value)) {
        result.push(key);
      }
    });
    return result.sort();
  }

  /**
   * Checks if the specified object `property` exists and is a direct property,
   * instead of an inherited property.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to check.
   * @param {String} property The property to check for.
   * @returns {Boolean} Returns `true` if key is a direct property, else `false`.
   * @example
   *
   * _.has({ 'a': 1, 'b': 2, 'c': 3 }, 'b');
   * // => true
   */
  function has(object, property) {
    return object ? hasOwnProperty.call(object, property) : false;
  }

  /**
   * Creates an object composed of the inverted keys and values of the given `object`.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to invert.
   * @returns {Object} Returns the created inverted object.
   * @example
   *
   *  _.invert({ 'first': 'moe', 'second': 'larry' });
   * // => { 'moe': 'first', 'larry': 'second' } (order is not guaranteed)
   */
  function invert(object) {
    var index = -1,
        props = keys(object),
        length = props.length,
        result = {};

    while (++index < length) {
      var key = props[index];
      result[object[key]] = key;
    }
    return result;
  }

  /**
   * Checks if `value` is a boolean value.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is a boolean value, else `false`.
   * @example
   *
   * _.isBoolean(null);
   * // => false
   */
  function isBoolean(value) {
    return value === true || value === false || toString.call(value) == boolClass;
  }

  /**
   * Checks if `value` is a date.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is a date, else `false`.
   * @example
   *
   * _.isDate(new Date);
   * // => true
   */
  function isDate(value) {
    return value instanceof Date || toString.call(value) == dateClass;
  }

  /**
   * Checks if `value` is a DOM element.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is a DOM element, else `false`.
   * @example
   *
   * _.isElement(document.body);
   * // => true
   */
  function isElement(value) {
    return value ? value.nodeType === 1 : false;
  }

  /**
   * Checks if `value` is empty. Arrays, strings, or `arguments` objects with a
   * length of `0` and objects with no own enumerable properties are considered
   * "empty".
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Array|Object|String} value The value to inspect.
   * @returns {Boolean} Returns `true`, if the `value` is empty, else `false`.
   * @example
   *
   * _.isEmpty([1, 2, 3]);
   * // => false
   *
   * _.isEmpty({});
   * // => true
   *
   * _.isEmpty('');
   * // => true
   */
  function isEmpty(value) {
    var result = true;
    if (!value) {
      return result;
    }
    var className = toString.call(value),
        length = value.length;

    if ((className == arrayClass || className == stringClass ||
        className == argsClass) ||
        (className == objectClass && typeof length == 'number' && isFunction(value.splice))) {
      return !length;
    }
    forOwn(value, function() {
      return (result = false);
    });
    return result;
  }

  /**
   * Performs a deep comparison between two values to determine if they are
   * equivalent to each other. If `callback` is passed, it will be executed to
   * compare values. If `callback` returns `undefined`, comparisons will be handled
   * by the method instead. The `callback` is bound to `thisArg` and invoked with
   * two arguments; (a, b).
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} a The value to compare.
   * @param {Mixed} b The other value to compare.
   * @param {Function} [callback] The function to customize comparing values.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @param- {Object} [stackA=[]] Internally used track traversed `a` objects.
   * @param- {Object} [stackB=[]] Internally used track traversed `b` objects.
   * @returns {Boolean} Returns `true`, if the values are equvalent, else `false`.
   * @example
   *
   * var moe = { 'name': 'moe', 'age': 40 };
   * var copy = { 'name': 'moe', 'age': 40 };
   *
   * moe == copy;
   * // => false
   *
   * _.isEqual(moe, copy);
   * // => true
   *
   * var words = ['hello', 'goodbye'];
   * var otherWords = ['hi', 'goodbye'];
   *
   * _.isEqual(words, otherWords, function(a, b) {
   *   var reGreet = /^(?:hello|hi)$/i,
   *       aGreet = _.isString(a) && reGreet.test(a),
   *       bGreet = _.isString(b) && reGreet.test(b);
   *
   *   return (aGreet || bGreet) ? (aGreet == bGreet) : undefined;
   * });
   * // => true
   */
  function isEqual(a, b, callback, thisArg, stackA, stackB) {
    // used to indicate that when comparing objects, `a` has at least the properties of `b`
    var whereIndicator = callback === indicatorObject;
    if (callback && !whereIndicator) {
      callback = typeof thisArg == 'undefined' ? callback : createCallback(callback, thisArg, 2);
      var result = callback(a, b);
      if (typeof result != 'undefined') {
        return !!result;
      }
    }
    // exit early for identical values
    if (a === b) {
      // treat `+0` vs. `-0` as not equal
      return a !== 0 || (1 / a == 1 / b);
    }
    var type = typeof a,
        otherType = typeof b;

    // exit early for unlike primitive values
    if (a === a &&
        (!a || (type != 'function' && type != 'object')) &&
        (!b || (otherType != 'function' && otherType != 'object'))) {
      return false;
    }
    // exit early for `null` and `undefined`, avoiding ES3's Function#call behavior
    // http://es5.github.com/#x15.3.4.4
    if (a == null || b == null) {
      return a === b;
    }
    // compare [[Class]] names
    var className = toString.call(a),
        otherClass = toString.call(b);

    if (className == argsClass) {
      className = objectClass;
    }
    if (otherClass == argsClass) {
      otherClass = objectClass;
    }
    if (className != otherClass) {
      return false;
    }
    switch (className) {
      case boolClass:
      case dateClass:
        // coerce dates and booleans to numbers, dates to milliseconds and booleans
        // to `1` or `0`, treating invalid dates coerced to `NaN` as not equal
        return +a == +b;

      case numberClass:
        // treat `NaN` vs. `NaN` as equal
        return a != +a
          ? b != +b
          // but treat `+0` vs. `-0` as not equal
          : (a == 0 ? (1 / a == 1 / b) : a == +b);

      case regexpClass:
      case stringClass:
        // coerce regexes to strings (http://es5.github.com/#x15.10.6.4)
        // treat string primitives and their corresponding object instances as equal
        return a == b + '';
    }
    var isArr = className == arrayClass;
    if (!isArr) {
      // unwrap any `lodash` wrapped values
      if (a.__wrapped__ || b.__wrapped__) {
        return isEqual(a.__wrapped__ || a, b.__wrapped__ || b, callback, thisArg, stackA, stackB);
      }
      // exit for functions and DOM nodes
      if (className != objectClass) {
        return false;
      }
      // in older versions of Opera, `arguments` objects have `Array` constructors
      var ctorA = a.constructor,
          ctorB = b.constructor;

      // non `Object` object instances with different constructors are not equal
      if (ctorA != ctorB && !(
            isFunction(ctorA) && ctorA instanceof ctorA &&
            isFunction(ctorB) && ctorB instanceof ctorB
          )) {
        return false;
      }
    }
    // assume cyclic structures are equal
    // the algorithm for detecting cyclic structures is adapted from ES 5.1
    // section 15.12.3, abstract operation `JO` (http://es5.github.com/#x15.12.3)
    stackA || (stackA = []);
    stackB || (stackB = []);

    var length = stackA.length;
    while (length--) {
      if (stackA[length] == a) {
        return stackB[length] == b;
      }
    }
    var size = 0;
    result = true;

    // add `a` and `b` to the stack of traversed objects
    stackA.push(a);
    stackB.push(b);

    // recursively compare objects and arrays (susceptible to call stack limits)
    if (isArr) {
      length = a.length;
      size = b.length;

      // compare lengths to determine if a deep comparison is necessary
      result = size == a.length;
      if (!result && !whereIndicator) {
        return result;
      }
      // deep compare the contents, ignoring non-numeric properties
      while (size--) {
        var index = length,
            value = b[size];

        if (whereIndicator) {
          while (index--) {
            if ((result = isEqual(a[index], value, callback, thisArg, stackA, stackB))) {
              break;
            }
          }
        } else if (!(result = isEqual(a[size], value, callback, thisArg, stackA, stackB))) {
          break;
        }
      }
      return result;
    }
    // deep compare objects using `forIn`, instead of `forOwn`, to avoid `Object.keys`
    // which, in this case, is more costly
    forIn(b, function(value, key, b) {
      if (hasOwnProperty.call(b, key)) {
        // count the number of properties.
        size++;
        // deep compare each property value.
        return (result = hasOwnProperty.call(a, key) && isEqual(a[key], value, callback, thisArg, stackA, stackB));
      }
    });

    if (result && !whereIndicator) {
      // ensure both objects have the same number of properties
      forIn(a, function(value, key, a) {
        if (hasOwnProperty.call(a, key)) {
          // `size` will be `-1` if `a` has more properties than `b`
          return (result = --size > -1);
        }
      });
    }
    return result;
  }

  /**
   * Checks if `value` is, or can be coerced to, a finite number.
   *
   * Note: This is not the same as native `isFinite`, which will return true for
   * booleans and empty strings. See http://es5.github.com/#x15.1.2.5.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is finite, else `false`.
   * @example
   *
   * _.isFinite(-101);
   * // => true
   *
   * _.isFinite('10');
   * // => true
   *
   * _.isFinite(true);
   * // => false
   *
   * _.isFinite('');
   * // => false
   *
   * _.isFinite(Infinity);
   * // => false
   */
  function isFinite(value) {
    return nativeIsFinite(value) && !nativeIsNaN(parseFloat(value));
  }

  /**
   * Checks if `value` is a function.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is a function, else `false`.
   * @example
   *
   * _.isFunction(_);
   * // => true
   */
  function isFunction(value) {
    return typeof value == 'function';
  }
  // fallback for older versions of Chrome and Safari
  if (isFunction(/x/)) {
    isFunction = function(value) {
      return value instanceof Function || toString.call(value) == funcClass;
    };
  }

  /**
   * Checks if `value` is the language type of Object.
   * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is an object, else `false`.
   * @example
   *
   * _.isObject({});
   * // => true
   *
   * _.isObject([1, 2, 3]);
   * // => true
   *
   * _.isObject(1);
   * // => false
   */
  function isObject(value) {
    // check if the value is the ECMAScript language type of Object
    // http://es5.github.com/#x8
    // and avoid a V8 bug
    // http://code.google.com/p/v8/issues/detail?id=2291
    return value ? objectTypes[typeof value] : false;
  }

  /**
   * Checks if `value` is `NaN`.
   *
   * Note: This is not the same as native `isNaN`, which will return `true` for
   * `undefined` and other values. See http://es5.github.com/#x15.1.2.4.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true`, if the `value` is `NaN`, else `false`.
   * @example
   *
   * _.isNaN(NaN);
   * // => true
   *
   * _.isNaN(new Number(NaN));
   * // => true
   *
   * isNaN(undefined);
   * // => true
   *
   * _.isNaN(undefined);
   * // => false
   */