def METHOD_NAME(directory: Optional[StrPath] = None) -> StrPath:
    """Initialize the duckdb index directory.
    If directory is None, it will be set to the default duckdb index location on the machine.
    Args:
        directory (Optional[Union[str, PathLike[str]]], optional): The directory to initialize. Defaults to None.
    Returns:
        Union[str, PathLike[str]]: The directory.
    """
    return init_dir(directory, appname=DUCKDB_INDEX_CACHE_APPNAME)