code: function addClass(controls) {
        var settings = Glide.settings;
        var item = controls[Glide.index];
  
        if (item) {
          item.classList.add(settings.classes.activeNav);
  
          siblings(item).forEach(function (sibling) {
            sibling.classList.remove(settings.classes.activeNav);
          });
        }
      }
docs: Toggles active class on items inside navigation.
  
  @param  {HTMLElement} controls
  @return {Void}