Updates the given rules and stores
        them on the router.

def _update(self, rules: list):
        """
        Updates the given rules and stores
        them on the router.
        """
        self._rules = rules
        to_store = '\n'.join(
            rule.config_string
            for rule in rules
        )
        sftp_connection = self._sftp_connection
        with sftp_connection.open(self.RULE_PATH, mode='w') as file_handle:
            file_handle.write(to_store)