code: func (e *Adaptor) checkForArduino() error {
  	if err := e.exportTristatePin(); err != nil {
  		return err
  	}
  	return nil
  }
docs: // TODO: also check to see if device labels for
  // /sys/class/gpio/gpiochip{200,216,232,248}/label == "pcal9555a"