docs: public static void main(String args[]) throws InterruptedException, IOException {
  
          System.out.println("<--Pi4J--> Pibrella Example ... started.");
  
          // -----------------------------------------------------------------
          // create a button listener
          // -----------------------------------------------------------------
          pibrella.button().addListener(new ButtonPressedListener() {
              @Override
              public void onButtonPressed(ButtonEvent event) {
                  System.out.println("[BUTTON PRESSED]");
                  pulseRate = 30;
  
                  // START or STOP sample tune
                  if(sampleTuneThread.isAlive())
                      stopSampleTune();
                  else
                      playSampleTune();
              }
          });
  
          pibrella.button().addListener(new ButtonReleasedListener() {
              @Override
              public void onButtonReleased(ButtonEvent event) {
                  System.out.println("[BUTTON RELEASED]");
                  pulseRate = 100;
              }
          });
  
          // run continuously until user aborts with CTRL-C
          while(true) {
  
              // step up the ladder
              for(int index = PibrellaLed.RED.getIndex(); index <= PibrellaLed.GREEN.getIndex(); index++) {
                  pibrella.getLed(index).pulse(pulseRate, true);
                  //Thread.sleep(pulseRate);
              }
  
              // step down the ladder
              for(int index = PibrellaLed.GREEN.getIndex(); index >= PibrellaLed.RED.getIndex(); index--) {
                  pibrella.getLed(index).pulse(pulseRate, true);
                  //Thread.sleep(pulseRate);
              }
          }
  
          // stop all GPIO activity/threads by shutting down the GPIO controller
          // (this method will forcefully shutdown all GPIO monitoring threads and scheduled tasks)
          //gpio.shutdown();  // <-- uncomment if your program terminates
      }