class Node : Object {
    public Node prev;
    public weak Node next;

    public Node (Node? prev = null) {
        this.prev = prev;      // ref
        if (prev != null) {
            prev.next = this;  // ref
        }
    }
}

/*
void main () {
    var n1 = new Node ();    // ref
    var n2 = new Node (n1);  // ref

    // print the reference count of both objects
    stdout.printf ("%u, %u\n", n1.ref_count, n2.ref_count);

}   // unref, unref
*/

void main () {
    while (true) {
        var n1 = new Node ();
        var n2 = new Node (n1);
        Thread.usleep (100);
    }
}