And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event
            (e.g. "payment successful").
    """

    ),
) -> None:
    """
    Build the docs for a language.
    """
    insiders_env_file = os.environ.get("INSIDERS_FILE")
    print(f"Insiders file {insiders_env_file}")
    if is_mkdocs_insiders():
        print("Using insiders")
    lang_path: Path = Path("docs") / lang
    if not lang_path.is_dir():
        typer.echo(f"The language translation doesn't seem to exist yet: {lang}")