src/transformers/commands/add_new_model.py/AddNewModelCommand/register_subcommand
class AddNewModelCommand:    def register_subcommand(parser: ArgumentParser):
        add_new_model_parser = parser.add_parser("add-new-model")
        add_new_model_parser.add_argument("--testing", action="store_true", help="If in testing mode.")
        add_new_model_parser.add_argument("--testing_file", type=str, help="Configuration file on which to run.")
        add_new_model_parser.add_argument(
            "--path", type=str, help="Path to cookiecutter. Should only be used for testing purposes."
        )
        add_new_model_parser.set_defaults(func=add_new_model_command_factory)