function guid() {
  /*jshint -W016 */
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    var r = Math.random()*16|0;
    var v = (c === 'x' ? r : (r&0x3|0x8));
    return v.toString(16);
  });
  /*jshint +W016 */
}
Creates an RFC4122 version 4 compliant GUID.

@static
@memberOf _
@category String
@returns {string} Returns the GUID.