vm_action method of HVClient can take arbitrary arguments

        # Unregister the children from the tags database:

        self._server.db.unregister(child)

    def vm_action(self, action, vms):

        return self.conn.call(action, vms)

    def vm_action(self, action, vms, *args, **kwargs):

        return self.conn.call(action, vms, *args, **kwargs)

    def sub_tags_register(self, obj_id, name, ttl=None, value=None):

        """ Register a new remote tag for a child of the client.