code: public static void apply(Element element, int offset, Functions.Func callback) {
          MaterialScrollfire scrollfire = new MaterialScrollfire();
          scrollfire.setElement(element);
          scrollfire.setCallback(callback);
          scrollfire.setOffset(offset);
          scrollfire.apply();
      }
docs: Executes callback method depending on how far into the page you've scrolled
  
  @param element  Target element that is being tracked
  @param offset   If this is 0, the callback will be fired when the selector element is at the very bottom of the user's window.
  @param callback The method to be called when the scrollfire is applied