def METHOD_NAME(folder: Path, suffix: Optional[str] = None) -> List[Path]:
    folder = folder.expanduser()
    files: List[Path] = [folder / file for file in os.listdir(folder)]
    files = [file for file in files if file.is_file()]
    if suffix:
        files = [file for file in files if str(file).lower().endswith(suffix.lower())]
    return files