/node_modules/grunt/node_modules/lodash/lodash.js

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/*!
 * Lo-Dash v0.9.2 <http://lodash.com>
 * (c) 2012 John-David Dalton <http://allyoucanleet.com/>
 * Based on Underscore.js 1.4.2 <http://underscorejs.org>
 * (c) 2009-2012 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 `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 = [],
      // avoid a Closure Compiler bug by creatively creating an object
      objectRef = new function(){};

  /** 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 detect template delimiter values that require a with-statement */
  var reComplexDelimiter = /[-?+=!~*%&^<>|{(\/]|\[\D|\b(?:delete|in|instanceof|new|typeof|void)\b/;

  /** Used to match HTML entities */
  var reEscapedHtml = /&(?:amp|lt|gt|quot|#x27);/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 insert the data object variable into compiled template source */
  var reInsertVariable = /(?:__e|__t = )\(\s*(?![\d\s"']|this\.)/g;

  /** 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 = /\$\{((?:(?=\\?)\\?[\s\S])*?)}/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 fix the JScript [[DontEnum]] bug */
  var shadowed = [
    'constructor', 'hasOwnProperty', 'isPrototypeOf', 'propertyIsEnumerable',
    'toLocaleString', 'toString', 'valueOf'
  ];

  /** 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,
      propertyIsEnumerable = objectRef.propertyIsEnumerable,
      slice = arrayRef.slice,
      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 the JScript [[DontEnum]] bug:
   *
   * In IE < 9 an objects own properties, shadowing non-enumerable ones, are
   * made non-enumerable as well.
   */
  var hasDontEnumBug;

  /** Detect if own properties are iterated after inherited properties (IE < 9) */
  var iteratesOwnLast;

  /**
   * Detect if `Array#shift` and `Array#splice` augment array-like objects
   * incorrectly:
   *
   * Firefox < 10, IE compatibility mode, and IE < 9 have buggy Array `shift()`
   * and `splice()` functions that fail to remove the last element, `value[0]`,
   * of array-like objects even though the `length` property is set to `0`.
   * The `shift()` method is buggy in IE 8 compatibility mode, while `splice()`
   * is buggy regardless of mode in IE < 9 and buggy in compatibility mode in IE 9.
   */
  var hasObjectSpliceBug = (hasObjectSpliceBug = { '0': 1, 'length': 1 },
    arrayRef.splice.call(hasObjectSpliceBug, 0, 1), hasObjectSpliceBug[0]);

  /** Detect if an `arguments` object's indexes are non-enumerable (IE < 9) */
  var noArgsEnum = true;

  (function() {
    var props = [];
    function ctor() { this.x = 1; }
    ctor.prototype = { 'valueOf': 1, 'y': 1 };
    for (var prop in new ctor) { props.push(prop); }
    for (prop in arguments) { noArgsEnum = !prop; }

    hasDontEnumBug = !/valueOf/.test(props);
    iteratesOwnLast = props[0] != 'x';
  }(1));

  /** Detect if an `arguments` object's [[Class]] is unresolvable (Firefox < 4, IE < 9) */
  var noArgsClass = !isArguments(arguments);

  /** Detect if `Array#slice` cannot be used to convert strings to arrays (Opera < 10.52) */
  var noArraySliceOnStrings = slice.call('x')[0] != 'x';

  /**
   * Detect lack of support for accessing string characters by index:
   *
   * IE < 8 can't access characters by index and IE 8 can only access
   * characters by index on string literals.
   */
  var noCharByIndex = ('x'[0] + Object('x')[0]) != 'xx';

  /**
   * Detect if a node's [[Class]] is unresolvable (IE < 9)
   * and that the JS engine won't error when attempting to coerce an object to
   * a string without a `toString` property value of `typeof` "function".
   */
  try {
    var noNodeClass = ({ 'toString': 0 } + '', toString.call(window.document || 0) == objectClass);
  } catch(e) { }

  /* Detect if `Function#bind` exists and is inferred to be fast (all but V8) */
  var isBindFast = nativeBind && /\n|Opera/.test(nativeBind + toString.call(window.opera));

  /* Detect if `Object.keys` exists and is inferred to be fast (IE, Opera, V8) */
  var isKeysFast = nativeKeys && /^.+$|true/.test(nativeKeys + !!window.attachEvent);

  /**
   * Detect if sourceURL syntax is usable without erroring:
   *
   * The JS engine in Adobe products, like InDesign, will throw a syntax error
   * when it encounters a single line comment beginning with the `@` symbol.
   *
   * The JS engine in Narwhal will generate the function `function anonymous(){//}`
   * and throw a syntax error.
   *
   * Avoid comments beginning `@` symbols in IE because they are part of its
   * non-standard conditional compilation support.
   * http://msdn.microsoft.com/en-us/library/121hztk3(v=vs.94).aspx
   */
  try {
    var useSourceURL = (Function('//@')(), !window.attachEvent);
  } catch(e) { }

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

  /** 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'
  };

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

  /**
   * The `lodash` function.
   *
   * @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
    if (value && 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.
     *
     * @static
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'escape': /<%-([\s\S]+?)%>/g,

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

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

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

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

  /**
   * 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 = template(
    // conditional strict mode
    '<% if (obj.useStrict) { %>\'use strict\';\n<% } %>' +

    // the `iteratee` may be reassigned by the `top` snippet
    'var index, value, iteratee = <%= firstArg %>, ' +
    // assign the `result` variable an initial value
    'result = <%= firstArg %>;\n' +
    // exit early if the first argument is falsey
    'if (!<%= firstArg %>) return result;\n' +
    // add code before the iteration branches
    '<%= top %>;\n' +

    // array-like iteration:
    '<% if (arrayLoop) { %>' +
    'var length = iteratee.length; index = -1;\n' +
    'if (typeof length == \'number\') {' +

    // add support for accessing string characters by index if needed
    '  <% if (noCharByIndex) { %>\n' +
    '  if (isString(iteratee)) {\n' +
    '    iteratee = iteratee.split(\'\')\n' +
    '  }' +
    '  <% } %>\n' +

    // iterate over the array-like value
    '  while (++index < length) {\n' +
    '    value = iteratee[index];\n' +
    '    <%= arrayLoop %>\n' +
    '  }\n' +
    '}\n' +
    'else {' +

    // object iteration:
    // add support for iterating over `arguments` objects if needed
    '  <%  } else if (noArgsEnum) { %>\n' +
    '  var length = iteratee.length; index = -1;\n' +
    '  if (length && isArguments(iteratee)) {\n' +
    '    while (++index < length) {\n' +
    '      value = iteratee[index += \'\'];\n' +
    '      <%= objectLoop %>\n' +
    '    }\n' +
    '  } else {' +
    '  <% } %>' +

    // Firefox < 3.6, Opera > 9.50 - Opera < 11.60, and Safari < 5.1
    // (if the prototype or a property on the prototype has been set)
    // incorrectly sets a function's `prototype` property [[Enumerable]]
    // value to `true`. Because of this Lo-Dash standardizes on skipping
    // the the `prototype` property of functions regardless of its
    // [[Enumerable]] value.
    '  <% if (!hasDontEnumBug) { %>\n' +
    '  var skipProto = typeof iteratee == \'function\' && \n' +
    '    propertyIsEnumerable.call(iteratee, \'prototype\');\n' +
    '  <% } %>' +

    // iterate own properties using `Object.keys` if it's fast
    '  <% if (isKeysFast && useHas) { %>\n' +
    '  var ownIndex = -1,\n' +
    '      ownProps = objectTypes[typeof iteratee] ? nativeKeys(iteratee) : [],\n' +
    '      length = ownProps.length;\n\n' +
    '  while (++ownIndex < length) {\n' +
    '    index = ownProps[ownIndex];\n' +
    '    <% if (!hasDontEnumBug) { %>if (!(skipProto && index == \'prototype\')) {\n  <% } %>' +
    '    value = iteratee[index];\n' +
    '    <%= objectLoop %>\n' +
    '    <% if (!hasDontEnumBug) { %>}\n<% } %>' +
    '  }' +

    // else using a for-in loop
    '  <% } else { %>\n' +
    '  for (index in iteratee) {<%' +
    '    if (!hasDontEnumBug || useHas) { %>\n    if (<%' +
    '      if (!hasDontEnumBug) { %>!(skipProto && index == \'prototype\')<% }' +
    '      if (!hasDontEnumBug && useHas) { %> && <% }' +
    '      if (useHas) { %>hasOwnProperty.call(iteratee, index)<% }' +
    '    %>) {' +
    '    <% } %>\n' +
    '    value = iteratee[index];\n' +
    '    <%= objectLoop %>;' +
    '    <% if (!hasDontEnumBug || useHas) { %>\n    }<% } %>\n' +
    '  }' +
    '  <% } %>' +

    // Because IE < 9 can't set the `[[Enumerable]]` attribute of an
    // existing property and the `constructor` property of a prototype
    // defaults to non-enumerable, Lo-Dash skips the `constructor`
    // property when it infers it's iterating over a `prototype` object.
    '  <% if (hasDontEnumBug) { %>\n\n' +
    '  var ctor = iteratee.constructor;\n' +
    '    <% for (var k = 0; k < 7; k++) { %>\n' +
    '  index = \'<%= shadowed[k] %>\';\n' +
    '  if (<%' +
    '      if (shadowed[k] == \'constructor\') {' +
    '        %>!(ctor && ctor.prototype === iteratee) && <%' +
    '      } %>hasOwnProperty.call(iteratee, index)) {\n' +
    '    value = iteratee[index];\n' +
    '    <%= objectLoop %>\n' +
    '  }' +
    '    <% } %>' +
    '  <% } %>' +
    '  <% if (arrayLoop || noArgsEnum) { %>\n}<% } %>\n' +

    // add code to the bottom of the iteration function
    '<%= bottom %>;\n' +
    // finally, return the `result`
    'return result'
  );

  /**
   * Reusable iterator options shared by `forEach`, `forIn`, and `forOwn`.
   */
  var forEachIteratorOptions = {
    'args': 'collection, callback, thisArg',
    'top': 'callback = createCallback(callback, thisArg)',
    'arrayLoop': 'if (callback(value, index, collection) === false) return result',
    'objectLoop': 'if (callback(value, index, collection) === false) return result'
  };

  /** Reusable iterator options for `defaults`, and `extend` */
  var extendIteratorOptions = {
    'useHas': false,
    'args': 'object',
    'top':
      'for (var argsIndex = 1, argsLength = arguments.length; argsIndex < argsLength; argsIndex++) {\n' +
      '  if (iteratee = arguments[argsIndex]) {',
    'objectLoop': 'result[index] = value',
    'bottom': '  }\n}'
  };

  /** Reusable iterator options for `forIn` and `forOwn` */
  var forOwnIteratorOptions = {
    'arrayLoop': null
  };

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

  /**
   * 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 || a === undefined) {
        return 1;
      }
      if (a < b || 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 `partailArgs` 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.
   * @returns {Function} Returns the new bound function.
   */
  function createBound(func, thisArg, partialArgs) {
    var isFunc = isFunction(func),
        isPartial = !partialArgs,
        methodName = func;

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

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

      if (!isFunc) {
        func = thisArg[methodName];
      }
      if (partialArgs.length) {
        args = args.length
          ? partialArgs.concat(slice.call(args))
          : partialArgs;
      }
      if (this instanceof bound) {
        // get `func` instance if `bound` is invoked in a `new` expression
        noop.prototype = func.prototype;
        thisBinding = new noop;

        // 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 an iteration callback bound to an optional `thisArg`. If `func` is
   * a property name, the callback will return the property value for a given element.
   *
   * @private
   * @param {Function|String} [func=identity|property] The function called per
   * iteration or property name to query.
   * @param {Mixed} [thisArg] The `this` binding of `callback`.
   * @returns {Function} Returns a callback function.
   */
  function createCallback(func, thisArg) {
    if (!func) {
      return identity;
    }
    if (typeof func != 'function') {
      return function(object) {
        return object[func];
      };
    }
    if (thisArg !== undefined) {
      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).
   *  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.
   *  arrayLoop - A string of code to execute in the array loop.
   *  objectLoop - 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 = {
      'arrayLoop': '',
      'bottom': '',
      'hasDontEnumBug': hasDontEnumBug,
      'isKeysFast': isKeysFast,
      'objectLoop': '',
      'noArgsEnum': noArgsEnum,
      'noCharByIndex': noCharByIndex,
      'shadowed': shadowed,
      '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, isString, objectTypes, ' +
        'nativeKeys, propertyIsEnumerable',
      'return function(' + args + ') {\n' + iteratorTemplate(data) + '\n}'
    );
    // return the compiled function
    return factory(
      createCallback, hasOwnProperty, isArguments, isString, objectTypes,
      nativeKeys, propertyIsEnumerable
    );
  }

  /**
   * 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];
  }

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

  /**
   * 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;
  }
  // fallback for browsers that can't detect `arguments` objects by [[Class]]
  if (noArgsClass) {
    isArguments = function(value) {
      return value ? hasOwnProperty.call(value, 'callee') : false;
    };
  }

  /**
   * 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 _
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} callback 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(forEachIteratorOptions, forOwnIteratorOptions, {
    'useHas': false
  });

  /**
   * Iterates over `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 _
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} callback 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(forEachIteratorOptions, forOwnIteratorOptions);

  /**
   * 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;
    }
    // IE < 9 presents DOM nodes as `Object` objects except they have `toString`
    // methods that are `typeof` "string" and still can coerce nodes to strings.
    // Also check that the constructor is `Object` (i.e. `Object instanceof Object`)
    var ctor = value.constructor;
    if ((!noNodeClass || !(typeof value.toString != 'function' && typeof (value + '') == 'string')) &&
        (!isFunction(ctor) || ctor instanceof ctor)) {
      // IE < 9 iterates inherited properties before own properties. If the first
      // iterated property is an object's own property then there are no inherited
      // enumerable properties.
      if (iteratesOwnLast) {
        forIn(value, function(value, key, object) {
          result = !hasOwnProperty.call(object, key);
          return false;
        });
        return result === false;
      }
      // 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;',
    "'": '&#x27;'
  };

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

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

  /**
   * Creates a clone of `value`. If `deep` is `true`, all nested objects will
   * also be cloned otherwise they will be assigned by reference. Functions, DOM
   * nodes, `arguments` objects, and objects created by constructors other than
   * `Object` are **not** cloned.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to clone.
   * @param {Boolean} deep A flag to indicate a deep clone.
   * @param- {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `deep`.
   * @param- {Array} [stackA=[]] Internally used to track traversed source objects.
   * @param- {Array} [stackB=[]] Internally used to associate clones with their
   *  source counterparts.
   * @returns {Mixed} Returns the cloned `value`.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * _.clone({ 'name': 'moe' });
   * // => { 'name': 'moe' }
   *
   * var shallow = _.clone(stooges);
   * shallow[0] === stooges[0];
   * // => true
   *
   * var deep = _.clone(stooges, true);
   * shallow[0] === stooges[0];
   * // => false
   */
  function clone(value, deep, guard, stackA, stackB) {
    if (value == null) {
      return value;
    }
    if (guard) {
      deep = false;
    }
    // inspect [[Class]]
    var isObj = isObject(value);
    if (isObj) {
      // don't clone `arguments` objects, functions, or non-object Objects
      var className = toString.call(value);
      if (!cloneableClasses[className] || (noArgsClass && isArguments(value))) {
        return value;
      }
      var isArr = className == arrayClass;
      isObj = isArr || (className == objectClass ? isPlainObject(value) : isObj);
    }
    // shallow clone
    if (!isObj || !deep) {
      // don't clone functions
      return isObj
        ? (isArr ? slice.call(value) : extend({}, value))
        : value;
    }

    var ctor = value.constructor;
    switch (className) {
      case boolClass:
      case dateClass:
        return new ctor(+value);

      case numberClass:
      case stringClass:
        return new ctor(value);

      case regexpClass:
        return ctor(value.source, reFlags.exec(value));
    }
    // 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
    var result = isArr ? ctor(value.length) : {};

    // 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)(value, function(objValue, key) {
      result[key] = clone(objValue, deep, null, stackA, stackB);
    });

    return result;
  }

  /**
   * Assigns enumerable properties of the default object(s) to the `destination`
   * object for all `destination` properties that resolve to `null`/`undefined`.
   * Once a property is set, additional defaults of the same property will be
   * ignored.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [default1, default2, ...] The default objects.
   * @returns {Object} Returns the destination object.
   * @example
   *
   * var iceCream = { 'flavor': 'chocolate' };
   * _.defaults(iceCream, { 'flavor': 'vanilla', 'sprinkles': 'rainbow' });
   * // => { 'flavor': 'chocolate', 'sprinkles': 'rainbow' }
   */
  var defaults = createIterator(extendIteratorOptions, {
    'objectLoop': 'if (result[index] == null) ' + extendIteratorOptions.objectLoop
  });

  /**
   * Assigns enumerable properties of the source object(s) to the `destination`
   * object. Subsequent sources will overwrite propery assignments of previous
   * sources.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [source1, source2, ...] The source objects.
   * @returns {Object} Returns the destination object.
   * @example
   *
   * _.extend({ 'name': 'moe' }, { 'age': 40 });
   * // => { 'name': 'moe', 'age': 40 }
   */
  var extend = createIterator(extendIteratorOptions);

  /**
   * 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', 'third': 'Curly' });
   * // => { 'Moe': 'first', 'Larry': 'second', 'Curly': 'third' } (order is not guaranteed)
   */
  function invert(object) {
    var result = {};
    forOwn(object, function(value, key) {
      result[value] = key;
    });
    return result;
  }

  /**
   * 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) {
    return toString.call(value) == arrayClass;
  };

  /**
   * Checks if `value` is a boolean (`true` or `false`) 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 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 || (noArgsClass && isArguments(value))) ||
        (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.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} a The value to compare.
   * @param {Mixed} b The other value to compare.
   * @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', 'luckyNumbers': [13, 27, 34] };
   * var clone = { 'name': 'moe', 'luckyNumbers': [13, 27, 34] };
   *
   * moe == clone;
   * // => false
   *
   * _.isEqual(moe, clone);
   * // => true
   */
  function isEqual(a, b, stackA, stackB) {
    // exit early for identical values
    if (a === b) {
      // treat `+0` vs. `-0` as not equal
      return a !== 0 || (1 / a == 1 / b);
    }
    // a strict comparison is necessary because `null == undefined`
    if (a == null || b == null) {
      return a === b;
    }
    // compare [[Class]] names
    var className = toString.call(a);
    if (className != toString.call(b)) {
      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 + '';
    }
    // exit early, in older browsers, if `a` is array-like but not `b`
    var isArr = className == arrayClass || className == argsClass;
    if (noArgsClass && !isArr && (isArr = isArguments(a)) && !isArguments(b)) {
      return false;
    }
    if (!isArr) {
      // unwrap any `lodash` wrapped values
      if (a.__wrapped__ || b.__wrapped__) {
        return isEqual(a.__wrapped__ || a, b.__wrapped__ || b);
      }
      // exit for functions and DOM nodes
      if (className != objectClass || (noNodeClass && (
          (typeof a.toString != 'function' && typeof (a + '') == 'string') ||
          (typeof b.toString != 'function' && typeof (b + '') == 'string')))) {
        return false;
      }
      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 index = -1,
        result = true,
        size = 0;

    // 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) {
      // compare 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--) {
          if (!(result = isEqual(a[size], b[size], stackA, stackB))) {
            break;
          }
        }
      }
      return result;
    }
    // deep compare objects
    for (var key in a) {
      if (hasOwnProperty.call(a, key)) {
        // count the number of properties.
        size++;
        // deep compare each property value.
        if (!(hasOwnProperty.call(b, key) && isEqual(a[key], b[key], stackA, stackB))) {
          return false;
        }
      }
    }
    // ensure both objects have the same number of properties
    for (key in b) {
      // The JS engine in Adobe products, like InDesign, has a bug that causes
      // `!size--` to throw an error so it must be wrapped in parentheses.
      // https://github.com/documentcloud/underscore/issues/355
      if (hasOwnProperty.call(b, key) && !(size--)) {
        // `size` will be `-1` if `b` has more properties than `a`
        return false;
      }
    }
    // handle JScript [[DontEnum]] bug
    if (hasDontEnumBug) {
      while (++index < 7) {
        key = shadowed[index];
        if (hasOwnProperty.call(a, key) &&
            !(hasOwnProperty.call(b, key) && isEqual(a[key], b[key], stackA, stackB))) {
          return false;
        }
      }
    }
    return true;
  }

  /**
   * 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.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a finite number, 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 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.
   *
   * @deprecated
   * @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
   */
  function isNaN(value) {
    // `NaN` as a primitive is the only value that is not equal to itself
    // (perform the [[Class]] check first to avoid errors with some host objects in IE)
    return toString.call(value) == numberClass && value != +value
  }

  /**
   * Checks if `value` is `null`.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is `null`, else `false`.
   * @example
   *
   * _.isNull(null);
   * // => true
   *
   * _.isNull(undefined);
   * // => false
   */
  function isNull(value) {
    return value === null;
  }

  /**
   * Checks if `value` is a number.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a number, else `false`.
   * @example
   *
   * _.isNumber(8.4 * 5);
   * // => true
   */
  function isNumber(value) {
    return toString.call(value) == numberClass;
  }

  /**
   * Checks if a given `value` is an object created by the `Object` constructor.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if `value` is a plain object, else `false`.
   * @example
   *
   * function Stooge(name, age) {
   *   this.name = name;
   *   this.age = age;
   * }
   *
   * _.isPlainObject(new Stooge('moe', 40));
   * // => false
   *
   * _.isPlainObject([1, 2, 3]);
   * // => false
   *
   * _.isPlainObject({ 'name': 'moe', 'age': 40 });
   * // => true
   */
  var isPlainObject = !getPrototypeOf ? shimIsPlainObject : function(value) {
    if (!(value && typeof value == 'object')) {
      return false;
    }
    var valueOf = value.valueOf,
        objProto = typeof valueOf == 'function' && (objProto = getPrototypeOf(valueOf)) && getPrototypeOf(objProto);

    return objProto
      ? value == objProto || (getPrototypeOf(value) == objProto && !isArguments(value))
      : shimIsPlainObject(value);
  };

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

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

  /**
   * Checks if `value` is `undefined`.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is `undefined`, else `false`.
   * @example
   *
   * _.isUndefined(void 0);
   * // => true
   */
  function isUndefined(value) {
    return value === undefined;
  }

  /**
   * 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) {
    // avoid iterating over the `prototype` property
    return typeof object == 'function' && propertyIsEnumerable.call(object, 'prototype')
      ? shimKeys(object)
      : (isObject(object) ? nativeKeys(object) : []);
  };

  /**
   * Merges enumerable properties of the source object(s) into the `destination`
   * object. Subsequent sources will overwrite propery assignments of previous
   * sources.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [source1, source2, ...] The source objects.
   * @param- {Object} [indicator] Internally used to indicate that the `stack`
   *  argument is an array of traversed objects instead of another source object.
   * @param- {Array} [stackA=[]] Internally used to track…

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