def correct_time_string(timeString):
    """
    Returns a valid string version of the time of departure/arrival based on
    given argument value

    If no-value is given, "ALL_DAY" will be returned

    :param timeString: String to correct
    :return: Corrected string value
    """
    if timeString == "BEFORE_NOON":
        return "BEFORE_NOON"

    elif timeString == "NOON_TO_6PM":
        return "NOON_TO_SIX"

    elif timeString == "AFTER_6PM":
        return "AFTER_SIX"

    else:
        return "ALL_DAY"