def _get_client(self):
        """
        OSS2 Auth client

        Returns:
            oss2.Auth or oss2.StsAuth: client
        """
        return (_oss.StsAuth if 'security_token' in self._storage_parameters
                else _oss.Auth if self._storage_parameters
                else _oss.AnonymousAuth)(**self._storage_parameters)
OSS2 Auth client

        Returns:
            oss2.Auth or oss2.StsAuth: client