function f6_drill_menu_fallback($args)
{
    /*
     * Instantiate new Page Walker class instead of applying a filter to the
     * "wp_page_menu" function in the event there are multiple active menus in theme.
     */
    $walker_page = new Walker_Page();
    $fallback = $walker_page->walk(get_pages(), 0);
    $fallback = str_replace("children", "children vertical menu", $fallback);
    echo '<ul class="vertical menu" data-drilldown="">' . $fallback . '</ul>';
}
function f6_topbar_menu_fallback($args)
{
    /*
     * Instantiate new Page Walker class instead of applying a filter to the
     * "wp_page_menu" function in the event there are multiple active menus in theme.
     */
    $walker_page = new Walker_Page();
    $fallback = $walker_page->walk(get_pages(), 0);
    $fallback = str_replace("<ul class='children'>", '<ul class="children submenu menu vertical" data-submenu>', $fallback);
    echo '<ul class="dropdown menu" data-dropdown-menu">' . $fallback . '</ul>';
}