php 无限分类函数

 $vo) {
        if ($pid == $vo['pid']) {
            $vo['position'] = str_repeat('▪', $lvl) . (1 + $lvl) . '岗 -' . $vo['position'];
            $res[] = $vo;
            $temp = $lvl + 1;
            
            selectTree($param, $vo['id'], $temp);
        }
    }
    return $res;
}