def mark_all_as_unread(self, recipient=None):
        qs = self.read(True)

        if recipient:
            qs = qs.filter(recipient=recipient)

        qs.update(unread=True)
Mark as unread any read messages in the current queryset.
dataset/ETHPy150Open django-notifications/django-notifications/notifications/models.py/NotificationQuerySet.mark_all_as_unread