struct Foo;

trait Bar {
    fn baz(&self);
}

impl Bar for Foo {
    fn baz(&self) {
        println!("hi");
    }
}

fn main() {
    let x: Box<Bar> = Box::new(Foo);
    let y: Box<Foo> = Box::new(Foo);

    println!("{:p} {:p}", x, y);
}