TNode::handle_back PHP Method

    public function handle_back($msg, $state)
    {
        $state['expected_msg']--;
        if (!empty($msg['value'])) {
            $state['children'] = array_merge($state['children'], $msg['value']);
        }
        if ($state['expected_msg'] == 0) {
            $pr = $state['parent'];
            if ($pr != $this->self()) {
                $state['children'][] = $this->getValue($state);
                $value_set = $state['children'];
                $this->send($pr, new Message('back', array('sender' => $this->self(), 'value' => $value_set)));
            } elseif ($pr == $this->self()) {
                $r = $this->compute($state['children']);
                echo sprintf("proc %s computed: %s\n", $state['name'], $r);
                $this->stop();
            }
        }
        return $state;
    }