def unread(self, include_deleted=False):
        if is_soft_delete() and not include_deleted:
            return self.filter(unread=True, deleted=False)
        else:
            """ when SOFT_DELETE=False, developers are supposed NOT to touch 'deleted' field.
            In this case, to improve query performance, don't filter by 'deleted' field
            """
            return self.filter(unread=True)
Return only unread items in the current queryset
dataset/ETHPy150Open django-notifications/django-notifications/notifications/models.py/NotificationQuerySet.unread