def lang_callback(lang: Optional[str]) -> Union[str, None]:
    if lang is None:
        return None
    lang = lang.lower()
    return lang


def complete_existing_lang(incomplete: str):
    lang_path: Path
    for lang_path in get_lang_paths():
        if lang_path.is_dir() and lang_path.name.startswith(incomplete):
            yield lang_path.name


@app.callback()
def callback() -> None:
    if is_mkdocs_insiders():

            """
        ),
    ] = None,
    init_oauth: Annotated[
        Optional[Dict[str, Any]],
        Doc(
            """
            A dictionary with Swagger UI OAuth2 initialization configurations.
            """
        ),
    ] = None,
    swagger_ui_parameters: Annotated[
        Optional[Dict[str, Any]],
        Doc(
            """