ode>Node</code>構造体定義はこんな見た目になりました:</p>
<!--
<span class="filename">Filename: src/main.rs</span>
-->
<p><span class="filename">ファイル名: src/main.rs</span></p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use std::rc::{Rc, Weak};
use std::cell::RefCell;

#[derive(Debug)]
struct Node {
    value: i32,
    parent: RefCell&lt;Weak&lt;Node&gt;&gt;,
    children: RefCell&lt;