Parse string in IB date or datetime format to datetime.

def parseIBDatetime(s):
    """
    Parse string in IB date or datetime format to datetime.
    """
    if len(s) == 8:
        # YYYYmmdd
        y = int(s[0:4])
        m = int(s[4:6])
        d = int(s[6:8])
        dt = datetime.date(y, m, d)
    elif s.isdigit():
        dt = datetime.datetime.fromtimestamp(
            int(s), datetime.timezone.utc)
    else:
        dt = datetime.datetime.strptime(s, '%Y%m%d  %H:%M:%S')
    return dt