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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def main(argv: typing.Optional[typing.Sequence] = None) -> typing.NoReturn: """Main entry point for the konch CLI."""

    args = parse_args(argv)

    if args["--debug"]:
        logging.basicConfig(
            format="%(levelname)s %(filename)s: %(message)s", level=logging.DEBUG
        )
    logger.debug(args)

    config_file: typing.Union[Path, None]
    if args["init"]:
        config_file = Path(args["<config_file>"] or CONFIG_FILE)
        init_config(config_file)
    else:
        config_file = Path(args["<config_file>"]) if args["<config_file>"] else None
        if args["edit"]:
            edit_config(config_file)
        elif args["allow"]:
            allow_config(config_file)
        elif args["deny"]:
            deny_config(config_file)

    mod = use_file(Path(args["--file"]) if args["--file"] else None)
    if hasattr(mod, "setup"):
        mod.setup()  # type: ignore

    if args["--name"]:
        if args["--name"] not in _config_registry:
            print_error(f'Invalid --name: "{args["--name"]}"')
            sys.exit(1)
        config_dict = _config_registry[args["--name"]]
        logger.debug(f'Using named config: "{args["--name"]}"')
        logger.debug(config_dict)
    else:
        config_dict = _cfg
    # Allow default shell to be overriden by command-line argument
    shell_name = args["--shell"]
    if shell_name:
        config_dict["shell"] = SHELL_MAP.get(shell_name.lower(), AutoShell)
    logger.debug(f"Starting with config {config_dict}")
    start(**config_dict)

    if hasattr(mod, "teardown"):
        mod.teardown()  # type: ignore
    sys.exit(0)