code: func (g *Driver) GetSerialNumber() (sNum string, err error) {
  	// read 20 bytes to get the serial number
  	response, err := g.readBytes(goPiGo3Address, GET_ID, 20)
  	if err != nil {
  		return sNum, err
  	}
  	if err := g.responseValid(response); err != nil {
  		return sNum, err
  	}
  	return fmt.Sprintf("%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X", response[4], response[5], response[6], response[7], response[8], response[9], response[10], response[11], response[12], response[13], response[14], response[15], response[16], response[17], response[18], response[19]), nil
  }
docs: // GetSerialNumber returns the 128-bit hardware serial number of the board.