code: func intToBytes(n int) []byte {
  	buf := make([]byte, 3)
  	buf[0] = byte((n >> 16) & 0xFF)
  	buf[1] = byte((n >> 8) & 0xFF)
  	buf[2] = byte(n & 0xFF)
  	return buf
  }
docs: // Encode packet data length to bytes(Big end)