code: func (b *Driver) SetTXPower(level int) (err error) {
  	buf := []byte{byte(level)}
  
  	err = b.adaptor().WriteCharacteristic(txPowerCharacteristic, buf)
  	if err != nil {
  		fmt.Println("SetTXLevel error:", err)
  		return err
  	}
  
  	return
  }
docs: // SetTXPower sets transmit level