def tearDown(self):
        super(SimpleInstanceTest, self).tearDown()
        CONF.network_label_regex = self.orig_conf
        CONF.ip_start = None
def expiration_datetime(self):
        """Datetime that the verification will expire. """
        days_good_for = settings.VERIFY_STUDENT["DAYS_GOOD_FOR"]
        return self.created_at + timedelta(days=days_good_for)