2 * Gets the timestamp of the number of milliseconds that have elapsed since
3 * the Unix epoch (1 January 1970 00:00:00 UTC).
9 * @returns {number} Returns the timestamp.
12 * _.defer(function(stamp) {
13 * console.log(_.now() - stamp);
15 * // => logs the number of milliseconds it took for the deferred function to be invoked