def __join_with_or(times):
    """Returns 'a', 'a or b', or 'a, b, or c'."""
    if not times:
        return ""
    if len(times) == 1:
        return times[0]
    if len(times) == 2:
        return " or ".join(times)
    return ", or ".join([", ".join(times[:-1]), times[-1]])