def _merge_known_related_objects(self, other):
        for field, objects in other._known_related_objects.items():
            self._known_related_objects.setdefault(field, {}).update(objects)
Keep track of all known related objects from either QuerySet instance.
dataset/ETHPy150Open django/django/django/db/models/query.py/QuerySet._merge_known_related_objects