Clean shutdown of the node.
        :param join: optionally wait for the process to end (default : True)
        :return: last exitcode from update method

def shutdown(self, join=True, timeout=None):
        """
        Clean shutdown of the node.
        :param join: optionally wait for the process to end (default : True)
        :return: last exitcode from update method
        """
        if self.interface is not None:
            self.interface.stop()

        return super(PyrosBase, self).shutdown(join, timeout=timeout)