code: def subcommand(self, command_name=None):
          
          def wrapper(decorated):
              cmd_name = command_name or decorated.__name__
              subparser = self.subparsers.add_parser(cmd_name,
                                                     description=decorated.__doc__)
              for args, kwargs in describe_arguments(decorated):
                  subparser.add_argument(*args, **kwargs)
              subparser.set_defaults(func=decorated)
              return decorated
          return wrapper
docs: Decorate a function as a subcommand. Use its arguments as the
          command-line arguments