protected function add_tabs( $tabs, $screen ) {
            foreach ( $tabs as $tab_slug => $tab_args ) {
                $tab = $screen->add( new Tab( $tab_slug, $tab_args ) );
                if ( is_wp_error( $tab ) ) {
                    self::doing_it_wrong( __METHOD__, $tab->get_error_message(), '0.5.0' );