def bulk_overwrite(self, entities_and_kinds):
EntityGroupMembership.objects.filter(entity_group=self).delete()<EOL>return self.bulk_add_entities(entities_and_kinds)<EOL>
Update the group to the given entities and sub-entity groups.

After this operation, the only members of this EntityGroup
will be the given entities, and sub-entity groups.

:type entities_and_kinds: List of (Entity, EntityKind) pairs.
:param entities_and_kinds: A list of entity, entity-kind pairs
    to set to the EntityGroup. 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.