#[derive(Debug)]
struct Heck<'a> {
    s: &'a mut String,
}

fn main() {
    let mut string = String::from("hey");
    let heck = Heck { s: &mut string };
    println!("{:?}", heck);

    heck.s.push('a');
    println!("{:?}", heck);

    // cannot borrow `*heck.s` as mutable, as it is behind a `&` reference
    // shared(&heck);
    // println!("{:?}", heck);
}

fn shared(heck: &Heck) {
    heck.s.push('a');
}