struct A;

impl A {
    fn b(&self, f: impl FnOnce()) {
        f()
    }
}

fn test() {
    let a = A;

    a.b(
      || {

   println!("sdflkdslkdkfmdslfdslkmdsflkmfdslkmfdsmlkfdsmlkfdslkfdsklfdslkmdsflfvdvjnlnlkccvjnxnlcvxjnlxcvjncvxjnkcvxjnxkcvz");
        }
    );
}