docs: function(params, callback) {
          /**
           * Callback for QB.pushnotifications.subscriptions.create(params, callback)
           * @callback createPushSubscriptionCallback
           * @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), type: 'POST', data: params}, callback);
      }