<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def on_message(self, name):
 """ Decorator for message listener callback functions. .. tip:: This is the most elegant way to define message listener callback functions. Use :py:func:`add_message_listener` only if you need to be able to :py:func:`remove the listener <remove_message_listener>` later. A decorated message listener function is called with three arguments every time the specified message is received: * ``self`` - the current vehicle. * ``name`` - the name of the message that was intercepted. * ``message`` - the actual message (a `pymavlink <http://www.qgroundcontrol.org/mavlink/pymavlink>`_ `class <https://www.samba.org/tridge/UAV/pymavlink/apidocs/classIndex.html>`_). For example, in the fragment below ``my_method`` will be called for every heartbeat message: .. code:: python @vehicle.on_message('HEARTBEAT') def my_method(self, name, msg):
 pass See :ref:`mavlink_messages` for more information. :param String name: The name of the message to be intercepted by the decorated listener function (or '*' to get all messages). """


        def decorator(fn):
            if isinstance(name, list):
                for n in name:
                    self.add_message_listener(n, fn)
            else:
                self.add_message_listener(name, fn)

        return decorator