medium_django_contenttypes.py

class ContentTypesConfig(AppConfig):
    name = 'django.contrib.contenttypes'
    verbose_name = _("Content Types")

    def ready(self):
        pre_migrate.connect(inject_rename_contenttypes_operations, sender=self)
        post_migrate.connect(create_contenttypes)
        checks.register(check_generic_foreign_keys, checks.Tags.models)
        checks.register(check_model_name_lengths, checks.Tags.models)