expand(treeviewMenu, parentLi) {\n      const expandedEvent = $.Event(Event.EXPANDED)\n\n      if (this._config.accordion) {\n        const openMenuLi   = parentLi.siblings(Selector.OPEN).first()\n        const openTreeview = openMenuLi.find(Selector.TREEVIEW_MENU).first()\n        this.collapse(openTreeview, openMenuLi)\n      }\n\n      treeviewMenu.stop().slideDown(this._config.animationSpeed, () => {\n        parentLi.addClass(ClassName.OPEN)\n        $(this._element).trigger(expandedEvent)\n      })\n\n...