code: function map(collection, iteratee) {
        var func = isArray(collection) ? arrayMap : baseMap;
        return func(collection, getIteratee(iteratee, 3));
      }
docs: Creates an array of values by running each element in `collection` thru
  `iteratee`. The iteratee is invoked with three arguments:
  (value, index|key, collection).
  
  Many lodash methods are guarded to work as iteratees for methods like
  `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`.
  
  The guarded methods are:
  `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`,
  `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`,
  `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`,
  `template`, `trim`, `trimEnd`, `trimStart`, and `words`
  
  @static
  @memberOf _
  @since 0.1.0
  @category Collection
  @param {Array|Object} collection The collection to iterate over.
  @param {Function} [iteratee=_.identity] The function invoked per iteration.
  @returns {Array} Returns the new mapped array.
  @example
  
  function square(n) {
  return n * n;
  }
  
  _.map([4, 8], square);
  // => [16, 64]
  
  _.map({ 'a': 4, 'b': 8 }, square);
  // => [16, 64] (iteration order is not guaranteed)
  
  var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
  ];
  
  // The `_.property` iteratee shorthand.
  _.map(users, 'user');
  // => ['barney', 'fred']