protected function add_menus( $menus ) {
            foreach ( $menus as $menu_slug => $menu_args ) {
                $menu = $this->add( new Menu( $menu_slug, $menu_args ) );
                if ( is_wp_error( $menu ) ) {
                    self::doing_it_wrong( __METHOD__, $menu->get_error_message(), '0.5.0' );