<?php
class Node {
    public $name;
    public $children;
    public $parent;
    function __construct($name) {
        $this->name = $name;
        $this->parent = null;
    }
    function insert($node) {
        $node->parent = $this;
        $this->children[] = $node;
    }
    function __destruct() {
        var_dump($this->name);
        unset($this->name);
        unset($this->children);
        unset($this->parent);
    }
}
$a = new Node('A');
$b = new Node('B');
$c = new Node('C');
$a->insert($b);
$a->insert($c);
unset($a);
unset($b);
unset($c);
var_dump(gc_collect_cycles());
echo "ok\n"
?>