Code shared from the Rust Playground

playground.rs

#[derive(Debug)]
struct Node<'a> {
    id: &'a str,
    children: Option<Vec<Node<'a>>>,
}

fn make_leaf<'a>(id: &'a str) -> Node<'a> {
    Node {
        id: id,
        children: None
    }
}

fn make_parent<'a>(id: &'a str, children: Vec<Node<'a>>) -> Node<'a> {
    Node {
        id: id,
        children: Some(children),
    }
}

fn main() {
    let l0 = make_leaf("l0");
    let l1 = make_leaf("l1");
    let n0 = make_parent("n0", vec![l0, l1]);
    let root = make_parent("root", vec![n0]);
    println!("{:?}", root);
}