docs: function(callback) {
          /**
           * Callback for QB.pushnotifications.subscriptions.list(callback)
           * @callback listPushSubscriptionCallback
           * @param {object} error - The error object
           * @param {object} response - Array of all existent user's subscriptions
           */
          this.service.ajax({url: Utils.getUrl(config.urls.subscriptions)}, callback);
      }