.version("0.0.1");

    let app = add_subcommand_args(app);

    let matches = app.clone().get_matches_safe().unwrap_or_else(|err| {

        let _ = ui.writeln_stderr_str(&err.message);

        std::process::exit(exitcode::UNIMPLEMENTED)

    });

    let (subcommand_name, subcommand_matches) = matches.subcommand();

    let run = subcommand_run_fn(subcommand_name)

        .expect("unknown subcommand name from clap despite AppSettings::SubcommandRequired");

    let args = subcommand_matches

        .expect("no subcommand arguments from clap despite AppSettings::SubcommandRequired");

    let result = (|| -> Result<(), CommandError> {

        let config = hg::config::Config::load()?;

        run(&ui, &config, args)

    })();

    let exit_code = match result {

macro_rules! subcommands {

    ($( $command: ident )+) => {

        mod commands {

            $(

                pub mod $command;

            )+

        }

        fn add_subcommand_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {

            app

            $(

                .subcommand(commands::$command::args())

            )+

        }

        fn subcommand_run_fn(name: &str) -> Option<fn(

            &ui::Ui,

            &hg::config::Config,

            &ArgMatches,

        ) -> Result<(), CommandError>> {

            match name {

                $(

                    stringify!($command) => Some(commands::$command::run),

                )+

                _ => None,

            }

    };

subcommands! {

    cat

    debugdata

    debugrequirements

    files

    root

}