def _load_generic(self, attrname):
        instance = self.__class__.get_by_uuid(self._context,
                                              uuid=self.uuid,
                                              expected_attrs=[attrname])

        # NOTE(danms): Never allow us to recursively-load
        if instance.obj_attr_is_set(attrname):
            self[attrname] = instance[attrname]
        else:
            raise exception.ObjectActionError(
                action='obj_load_attr',
                reason='loading %s requires recursion' % attrname)
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/objects/instance.py/Instance._load_generic/original