def filename_norm_split(filename: str) -> Tuple[str, str]:
    """
    Splits filename into basename and extension
    and lowercases results to enable simple lookup
    in a case-insensitive manner.

    Args:
        filename (str): Filename/Path to split

    Returns:
        Tuple[str,str]: file basename, file extension
    """
    file_basename = os.path.basename(filename).lower()
    file_parts = file_basename.split(".")
    if len(file_parts) > 1:
        file_ext = file_parts[-1]
    else:
        file_ext = ""
    return file_basename, file_ext

    Splits filename into basename and extension
    and lowercases results to enable simple lookup
    in a case-insensitive manner.

    Args:
        filename (str): Filename/Path to split

    Returns:
        Tuple[str,str]: file basename, file extension
    
python/aitemplate/backend/build_cache_base.py