code: def add_arguments(self, parser):
          
          group = parser.add_mutually_exclusive_group(required=True)
          group.add_argument('-d', '--downgrade', action='store_true',
                             help='downgrade the J-Link firmware')
          group.add_argument('-u', '--upgrade', action='store_true',
                             help='upgrade the J-Link firmware')
          return self.add_common_arguments(parser, False)
docs: Adds the arguments for the firmware command.
  
          Args:
            self (FirmwareCommand): the ``FirmwareCommand`` instance
            parser (argparse.ArgumentParser): parser to add the commands to
  
          Returns:
            ``None``