}
	return t.ext
}

// unixSec returns the time's seconds since Jan 1 1970 (Unix time).
func (t *Time) unixSec() int64 { return t.sec() + internalToUnix }

// addSec adds d seconds to the time.
func (t *Time) addSec(d int64) {
	if t.wall&hasMonotonic != 0 {
		sec := int64(t.wall << 1 >> (nsecShift + 1))
		dsec := sec + d
		if 0 <= dsec && dsec <= 1<<33-1 {

	}

	if z != nil {
		return Date(year, Month(month), day, hour, min, sec, nsec, z), nil
	}

	if zoneOffset != -1 {
		t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
		t.addSec(-int64(zoneOffset))

		// Look for local zone with the given offset.
		// If that zone was in effect at the given time, use it.
		name, offset, _, _, _ := local.lookup(t.unixSec())