code: func getBLEDevice(impl string) (d *blelib.Device, err error) {
  	if currentDevice != nil {
  		return currentDevice, nil
  	}
  
  	dev, e := defaultDevice(impl)
  	if e != nil {
  		return nil, errors.Wrap(e, "can't get device")
  	}
  	blelib.SetDefaultDevice(dev)
  
  	currentDevice = &dev
  	d = &dev
  	return
  }
docs: // getBLEDevice is singleton for blelib HCI device connection