docs: def get(self, request, format=None):
          """ get HTTP method """
          action = request.query_params.get('action', 'unread')
          # action can be only "unread" (default), "count" and "all"
          action = action if action == 'count' or action == 'all' else 'unread'
          # mark as read parameter, defaults to true
          mark_as_read = request.query_params.get('read', 'true') == 'true'
          # queryset
          notifications = self.get_queryset().filter(to_user=request.user)
          # pass to specific action
          return getattr(self, 'get_%s' % action)(request, notifications, mark_as_read)