def backwards(self, orm):
Return all matches, allowing matches from all subclasses of
dataset/ETHPy150Open hzlf/openbroadcast/website/apps/datatrans/migrations/0004_add_object_links.py/Migration.backwards--crossover with--dataset/ETHPy150Open evennia/evennia/evennia/typeclasses/managers.py/TypeclassManager.all_family