code: func readDate(rd *bufio.Reader) (int, time.Month, int, bool) {
  	year := rd.ReadUint16()
  	null := ((year & 0x8000) == 0) //null value
  	year &= 0x3fff
  	month := rd.ReadInt8()
  	month++
  	day := rd.ReadInt8()
  	return int(year), time.Month(month), int(day), null
  }
docs: // null values: most sig bit unset
  // year: unset second most sig bit (subtract 2^15)
  // --> read year as unsigned
  // month is 0-based
  // day is 1 byte