code: private OnClickListener createNextButtonListener() {
          return new OnClickListener() {
  
              @Override
              public void onClick(final View v) {
                  int selectedIndex = viewPager.getCurrentItem();
  
                  if (notifyOnNext(selectedIndex)) {
                      viewPager.setCurrentItem(selectedIndex + 1);
                  }
              }
  
          };
      }
docs: Creates and returns a listener, which allows to show the next fragment, when the
  corresponding button is clicked.
  
  @return The listener, which has been created, as an instance of the type {@link
  OnClickListener}