code: func (b *BatteryDriver) GetBatteryLevel() (level uint8) {
  	var l uint8
  	c, _ := b.adaptor().ReadCharacteristic("2a19")
  	buf := bytes.NewBuffer(c)
  	val, _ := buf.ReadByte()
  	l = uint8(val)
  	return l
  }
docs: // GetBatteryLevel reads and returns the current battery level