Argparse expects exit() to be a terminal function and not return.
        As such, this function must raise an exception which will be caught
        by Cmd.hasValidOpts.

def exit(self, status=0, message=None):
        '''
        Argparse expects exit() to be a terminal function and not return.
        As such, this function must raise an exception which will be caught
        by Cmd.hasValidOpts.
        '''
        self.exited = True
        if message is not None:
            self.mesgs.extend(message.split('\n'))
        raise s_exc.BadSyntax(mesg=message, prog=self.prog, status=status)