<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def quit(self, message=None):
 """ Quit network. """

        if message is None:
            message = self.DEFAULT_QUIT_MESSAGE

        await self.rawmsg('QUIT', message)
        await self.disconnect(expected=True)