docs: function getClientId() {
      if (window && window.device) {
          return window.device.uuid;
      }
      if (navigator && navigator.device) {
          return navigator.device.uuid;
      }
      if (window && window.localStorage) {
          var clientId = window.localStorage.getItem(CLIENT_ID_TAG);
          if (!clientId) {
              clientId = uuidGenerator();
              localStorage.setItem(CLIENT_ID_TAG, clientId);
          }
          return clientId;
      } else {
          throw Error("Cannot create and store client id");
      }
  }