def _extract_time(m):
    if not m:
        return 0, 0, 0
    hours = m.group('hours')
    if not hours:
        return 0, 0, 0
    hours = int(hours)
    minutes = int(m.group('minutes'))
    seconds = m.group('seconds')
    if seconds:
        seconds = int(seconds)
    else:
        seconds = 0
    return hours, minutes, seconds