def register_argument(self, *args, **kwargs):
self._argparse_argkwargs.append((args, kwargs))<EOL>
Register command-line argument.

All given arguments will be passed directly to
:meth:`argparse.ArgumentParser.add_argument` calls by
:meth:`load_arguments` method.

See :meth:`argparse.ArgumentParser.add_argument` documentation for
further information.