code: function initMenu() {
      let menuCfg = defaults.menu;
  
      // no configuration given and neither the menu created earlier
      // no need to proceed
      if (!menuCfg && !Menu.created) {
          return;
      }
  
      // set options to create menu
      if (menuCfg) {
          Menu.setOptions(menuCfg);
      }
  
      menuDoc = Menu.get();
      Page.prepareDom(menuDoc);
  }
docs: Initializes the menu document if present
  
  @private