internal/protocol/field.go
func writeDate(wr *bufio.Writer, t time.Time) {
	//store in utc
	utc := t.In(time.UTC)

	year, month, day := utc.Date()

	wr.WriteUint16(uint16(year) | 0x8000)
	wr.WriteInt8(int8(month) - 1)
	wr.WriteInt8(int8(day))
}
func writeDate(wr *bufio.Writer, t time.Time) {
	//store in utc
	utc := t.In(time.UTC)

	year, month, day := utc.Date()

	wr.WriteUint16(uint16(year) | 0x8000)
	wr.WriteInt8(int8(month) - 1)
	wr.WriteInt8(int8(day))
}
// year: set most sig bit
// month 0 based