Make sure the auth app only appears in the 'duashttp'
        database.

def allow_migrate(self, db, model):
        """
        Make sure the auth app only appears in the 'duashttp'
        database.
        """
        if db == DUAS_DB_ROUTE_PREFIX:
            return model._meta.app_label == 'duashttp'
        elif model._meta.app_label == 'duashttp':
            return False
        return None