def METHOD_NAME(self, db, app_label, model_name=None, **hints):
    """
    Make sure the 'auth', 'contenttypes', 'admin' and 'core.tenant' apps
    and models only appear in the 'default' database. Don't include any
    other model in that database.
    """
    if app_label in self.auth_app_labels:
        return db == 'default'
    elif app_label == 'core' and model_name == 'tenant':
        return db == 'default'
    elif db == 'default':
        return False
    else:
        return None