walk_page_tree( array $pages, int $depth, int $current_page, array $args )

function walk_page_tree( $pages, $depth, $current_page, $r ) {
	if ( empty($r['walker']) )
		$walker = new Walker_Page;
	else
		$walker = $r['walker'];

	foreach ( (array) $pages as $page ) {
		if ( $page->post_parent )
			$r['pages_with_children'][ $page->post_parent ] = true;
	}

	$args = array($pages, $depth, $r, $current_page);
	return call_user_func_array(array($walker, 'walk'), $args);
}