Вложенные подразделы menu средствами PHP

<?php
// Setting the menu parent
$parent = 0;

// Geting the first menu level 
$menu = $modx->getDocumentChildren($parent, 1, '0', 'id, menutitle, pagetitle', 'hidemenu = 0', 'menuindex');

// Getting second menu level
foreach ($menu as $key => $document) {
    $menu[$key]['children'] = $modx->getDocumentChildren($document['id'], 1, '0', 'id, menutitle, pagetitle', 'hidemenu = 0', 'menuindex');
}

// Forming output
$output = '<ul>';

foreach ($menu as $document_one) {

    $output .= '<li><a title="' . $document_one['pagetitle'] . '" href="' . $modx->makeUrl($document_one['id']) . '" class="aaa">' . $document_one['menutitle'] . '</a>';

    if (count($document_one['children'] != 0)) {
        $output .= '<ul>';
        
        foreach ($document_one['children'] as $document_two) {
            $output .= '<li><a title="' . $document_two['pagetitle'] . '" href="' . $modx->makeUrl($document_two['id']) . '" class="bbb">' . $document_two['menutitle'] . '</a></li>';
        }
        
        $output .= '</ul>';
    }
    
    $output .= '</li>';
}
$output .= '</ul>';

return $output;
?>