def tearDown(self):
        super(SimpleInstanceTest, self).tearDown()
        CONF.network_label_regex = self.orig_conf
        CONF.ip_start = None
def set_submodule(self, submodule: 'Submodule') -> None:
        """Set this instance's submodule. It must be called before
        the first write operation begins"""
        self._smref = weakref.ref(submodule)