def METHOD_NAME(zone_str):
    x = [
        datetime.datetime(*_dateval_tuple[:-2])
        .replace(tzinfo=zoneinfo.ZoneInfo(zone_str)),
    ] * 2
    res = robjects.POSIXct(x)
    assert list(res.slots['class']) == ['POSIXct', 'POSIXt']
    assert len(res) == 2
    assert res.slots['tzone'][0] == (zone_str if zone_str else '')