code: function KdbxUuid(ab) {
      if (ab === undefined) {
          ab = new ArrayBuffer(UuidLength);
      }
      if (typeof ab === 'string') {
          ab = ByteUtils.base64ToBytes(ab);
      }
      this.id = ab.byteLength === 16 ? ByteUtils.bytesToBase64(ab) : undefined;
      this.empty = true;
      if (ab) {
          var bytes = new Uint8Array(ab);
          for (var i = 0, len = bytes.length; i < len; i++) {
              if (bytes[i] !== 0) {
                  this.empty = false;
                  return;
              }
          }
      }
  }
docs: Uuid for passwords
  @param {ArrayBuffer|string} ab - ArrayBuffer with data
  @constructor