code: function(isVisible) {
                      var self = this,
                          $textEl = self.$el.find(self.options.toggleTextSelector);
  
                      if (isVisible) {
                          $textEl.text(self.$el.data('expanded-text'));
                      } else {
                          $textEl.text(self.$el.data('collapsed-text'));
                      }
                      $textEl.attr('aria-expanded', isVisible);
                      self.$el.toggleClass(self.options.isCollapsedClass, !isVisible);
                  }
docs: Toggles the visibility of the section.
  
  @param {boolean} isVisible True if the section should be visible (default: false).