def METHOD_NAME(message):
    """Global log message about rainbow grades."""
    today = datetime.datetime.now()
    log_file_path = Path(data_dir, 'logs', 'rainbow_grades',
                         "{:04d}{:02d}{:02d}.txt".format(today.year,
                                                         today.month,
                                                         today.day))
    # append to the file
    with open(log_file_path, 'a') as file:
        timestring = today.strftime("%Y-%m-%d %H:%M:%S%z")
        file.write(timestring + " " + message + "\n")