docs: def update_mailing_lists_in_m2m(
      sender=None,
      userprofile=None,
      pk_set=None,
      subscribe=None,
      unsubscribe=None,
      verbose=None,
      email_enabled=None,
  ):
      """
      m2m_model = m2m model class for 'email_notifications' or
      'sms_notifications'.
      """
      response = None
      email_enabled = email_enabled or settings.EMAIL_ENABLED
      if email_enabled and site_notifications.loaded:
          if userprofile.email_notifications.through == sender:
              NotificationModel = django_apps.get_model("edc_notification.Notification")
              for notification_obj in NotificationModel.objects.filter(
                  pk__in=list(pk_set), enabled=True
              ):
                  notification_cls = site_notifications.get(notification_obj.name)
                  notification = notification_cls()
                  manager = MailingListManager(
                      address=notification.email_to[0],
                      display_name=notification.display_name,
                      name=notification.name,
                  )
                  response = manager.create(verbose=verbose)
                  if subscribe:
                      response = manager.subscribe(userprofile.user, verbose=verbose)
                  elif unsubscribe:
                      response = manager.unsubscribe(userprofile.user, verbose=verbose)
      return response