trait X {
    fn x(&self) -> i32;
}
trait Y {
    fn y(&self) -> i32;
}

// question: i have implemented X for Y, so
// shouldn't this mean all instances of Y are
// also X?
impl X for Y {
    fn x(&self) -> i32 {
        123
    }
}

// question: here i have a struct Z, and I
// implement Y for Z, and Y implements X, so
// shouldn't X by implemented for Z by way of
// Y?
struct Z;
impl Y for Z {
    fn y(&self) -> i32 {
        0
    }
}

fn test(y: Box<dyn Y>) {
    println!("{}", y.x());
}

fn main() {
    let z = Box::new(Z);
    test(z);

}