code: function getSubscriberByEmail(options) {
              if (options.email) {
                  return models.Subscriber.getByEmail(options.email, options)
                      .then((subscriber) => {
                          if (!subscriber) {
                              return Promise.reject(new common.errors.NotFoundError({
                                  message: common.i18n.t('errors.api.subscribers.subscriberNotFound')
                              }));
                          }
  
                          options.id = subscriber.get('id');
                          return options;
                      });
              }
  
              return options;
          }
docs: ### Delete Subscriber
  If we have an email param, check the subscriber exists
  @type {[type]}