code: def _message_queryset(self, include_read=False):
          
          expire = timezone.now()
  
  
          qs = PersistentMessage.objects.\
          filter(user=self.get_user()).\
          filter(Q(expires=None) | Q(expires__gt=expire))
          if not include_read:
              qs = qs.exclude(read=True)
          return qs
docs: Return a queryset of messages for the request user