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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def hydrate_datetime(seconds, nanoseconds, tz=None):
 """ Hydrator for `DateTime` and `LocalDateTime` values. :param seconds: :param nanoseconds: :param tz: :return: datetime """

    minutes, seconds = map(int, divmod(seconds, 60))
    hours, minutes = map(int, divmod(minutes, 60))
    days, hours = map(int, divmod(hours, 24))
    seconds = (1000000000 * seconds + nanoseconds) / 1000000000
    t = DateTime.combine(Date.from_ordinal(UNIX_EPOCH_DATE_ORDINAL + days), Time(hours, minutes, seconds))
    if tz is None:
        return t
    if isinstance(tz, int):
        tz_offset_minutes, tz_offset_seconds = divmod(tz, 60)
        zone = FixedOffset(tz_offset_minutes)
    else:
        zone = timezone(tz)
    return zone.localize(t)