timePartDay            = "DAY"
	timePartHour           = "HOUR"
	timePartMinute         = "MINUTE"
	timePartSecond         = "SECOND"
	timePartTimezoneHour   = "TIMEZONE_HOUR"
	timePartTimezoneMinute = "TIMEZONE_MINUTE"
)

func extract(what string, t time.Time) (v *Value, err error) {
	switch what {
	case timePartYear:
		return FromInt(int64(t.Year())), nil
	case timePartMonth:
		return FromInt(int64(t.Month())), nil