def bulk_add_entities(self, entities_and_kinds):
memberships = [EntityGroupMembership(<EOL>entity_group=self,<EOL>entity=entity,<EOL>sub_entity_kind=sub_entity_kind,<EOL>) for entity, sub_entity_kind in entities_and_kinds]<EOL>created = EntityGroupMembership.objects.bulk_create(memberships)<EOL>return created<EOL>
Add many entities and sub-entity groups to this EntityGroup.

:type entities_and_kinds: List of (Entity, EntityKind) pairs.
:param entities_and_kinds: A list of entity, entity-kind pairs
    to add to the group. In the pairs the entity-kind can be
    ``None``, to add a single entity, or some entity kind to
    add all sub-entities of that kind.