trait HasS {
    fn get_s(&self) -> String;
}

struct Foo {}

impl HasS for Foo {
    fn get_s(&self) -> String {
        String::from("Foo")
    }
}

impl HasS for &Foo {
    fn get_s(&self) -> String {
        String::from("*Foo")
    }
}

fn main() {
    let foo = Foo{};
    println!("{}", foo.get_s());
    println!("{}", (&&foo).get_s());
}