function map(collection, iteratee, thisArg) {
	      var func = isArray(collection) ? arrayMap : baseMap;
	      iteratee = getCallback(iteratee, thisArg, 3);
	      return func(collection, iteratee);
	    }
Creates an array of values by running each element in `collection` through
`iteratee`. The `iteratee` is bound to `thisArg` and invoked with three
arguments; (value, index|key, collection).

If a property name is provided for `predicate` the created "_.property"
style callback returns the property value of the given element.

If an object is provided for `predicate` the created "_.matches" style
callback returns `true` for elements that have the properties of the given
object, else `false`.

@static
@memberOf _
@alias collect
@category Collection
@param {Array|Object|string} collection The collection to iterate over.
@param {Function|Object|string} [iteratee=_.identity] The function invoked
 per iteration. If a property name or object is provided it is used to
 create a "_.property" or "_.matches" style callback respectively.
@param {*} [thisArg] The `this` binding of `iteratee`.
@returns {Array} Returns the new mapped array.
@example

_.map([1, 2, 3], function(n) { return n * 3; });
// => [3, 6, 9]

_.map({ 'one': 1, 'two': 2, 'three': 3 }, function(n) { return n * 3; });
// => [3, 6, 9] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// using the "_.property" callback shorthand
_.map(users, 'user');
// => ['barney', 'fred']