export function guid():string {
  return 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
      var r = Math.random() * 16 | 0,
          v = c == 'x' ? r : (r & 0x3 | 0x8);
      return v.toString(16);
  });
}
