import datetime

EPOCH = 1970
_EPOCH_ORD = datetime.date(EPOCH, 1, 1).toordinal()

def timegm(tuple):
    """Unrelated but handy function to calculate Unix timestamp from GMT."""
    year, month, day, hour, minute, second = tuple[:6]
    days = datetime.date(year, month, 1).toordinal() - _EPOCH_ORD + day - 1
    hours = days*24 + hour
    minutes = hours*60 + minute
    seconds = minutes*60 + second
    return seconds

