1 (function (GCN) {
  2 
  3 	'use strict';
  4 
  5 	/**
  6 	 * Only grows, never shrinks.
  7 	 * @private
  8 	 * @type {number}
  9 	 */
 10 	var uniqueIdCounter = 0;
 11 
 12 	/**
 13 	 * Generates a unique id with an optional prefix.
 14 	 *
 15 	 * The returned value is only unique among other returned values,
 16 	 * not globally.
 17 	 *
 18 	 * @public
 19 	 * @param {string}
 20 	 *        Optional prefix for the id to be generated.
 21 	 * @return {string}
 22 	 *        Never the same string more than once.
 23 	 */
 24 	function uniqueId(prefix) {
 25 		return (prefix || '') + (++uniqueIdCounter);
 26 	}
 27 
 28 	GCN.uniqueId = uniqueId;
 29 
 30 }(GCN));
 31