code: function( timeout, callback ) {
  			if ( typeof timeout === 'function' ) {
  				callback = timeout;
  				timeout = null;
  			}
  			timeout = timeout || 600;
  			var self = this;
  			this.queue.unshift(function() {
  				setTimeout(function() {
  					callback && callback.apply(self, [])
  					self.done.apply(self, arguments);
  				}, timeout);
  			});
  			return this;
  		}
docs: Delays the next command a set timeout.
  @param {Number} [timeout]
  @param {Function} [callback]