WordPress at a glance
function is not described

walk_nav_menu_tree() WP 3.0.0

Retrieve the HTML list content for nav menu items.

No Hooks.

Return

String. The HTML list content for the menu items.

Usage

walk_nav_menu_tree( $items, $depth, $r );
$items(array) (required)
The menu items, sorted by each menu item's menu order.
$depth(int) (required)
Depth of the item in reference to parents.
$r(stdClass) (required)
An object containing wp_nav_menu() arguments.

Code of walk nav menu tree: wp-includes/nav-menu-template.php VER 5.0.3

<?php
function walk_nav_menu_tree( $items, $depth, $r ) {
	$walker = ( empty($r->walker) ) ? new Walker_Nav_Menu : $r->walker;
	$args = array( $items, $depth, $r );

	return call_user_func_array( array( $walker, 'walk' ), $args );
}