def forwards(self, orm):
        for storage in orm.Storage.objects.all():
            storage_hash = self.get_storage_hash(storage)
            orm.Source.objects.filter(storage=storage).update(
                                        storage_hash=storage_hash)
            orm.Thumbnail.objects.filter(storage=storage).update(
                                        storage_hash=storage_hash)
Write your forwards methods here.
dataset/ETHPy150Open SmileyChris/easy-thumbnails/easy_thumbnails/south_migrations/0012_build_storage_hashes.py/Migration.forwards