Register the models and assign them to `models`
        :return:

def _expose_models(cls):
        """
        Register the models and assign them to `models`
        :return: 
        """
        if db._IS_OK_:
            register_models(**{m.__name__: m
                               for m in db.Model.__subclasses__()
                               if not hasattr(models, m.__name__)})