g">    value: i32,
</span><span class="boring">    parent: RefCell&lt;Weak&lt;Node&gt;&gt;,
</span><span class="boring">    children: RefCell&lt;Vec&lt;Rc&lt;Node&gt;&gt;&gt;,
</span><span class="boring">}
</span><span class="boring">
</span>fn main() {
    let leaf = Rc::new(Node {
        value: 3,
        parent: RefCell::new(Weak::new()),
        children: RefCell::new(vec![]),
    });

    println!(
        // leafのstrong_count = {}, weak_count = {}
        &quot;leaf strong = {}, weak = {}&quot;,
  