trait empty {}

trait Ass {
    type A;
    type B;
}

#[derive(Debug)]
struct Unit;

impl Ass for Unit {
    type A = Self;
    type B = u8;
}

impl Iterator for Unit {
    type Item = Self;
    fn next(&mut self) -> Option<Self::Item> {
        Some(Unit)
    }
}

fn main(){
    println!("ass");
    let unit = Unit;
    let mut a : <Unit as Ass>::A = Unit;
    let b : <Unit as Ass>::B = 8;
    let b = a.next().unwrap();
    println!("{:?}", b);
}