def timegm(year, month, day, hour, minute, second):
    """
    Convert time tuple in GMT to seconds since epoch, GMT
    """
    EPOCH = 1970
    if year < EPOCH:
        raise ValueError("Years prior to %d not supported" % (EPOCH,))
    assert 1 <= month <= 12
    days = 365*(year-EPOCH) + calendar.leapdays(EPOCH, year)
    for i in range(1, month):
        days = days + calendar.mdays[i]
    if month > 2 and calendar.isleap(year):
        days = days + 1
    days = days + day - 1
    hours = days*24 + hour
    minutes = hours*60 + minute
    seconds = minutes*60 + second
    return seconds

    Convert time tuple in GMT to seconds since epoch, GMT
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/http.py