pub trait Hash {
    fn hash(&self) -> usize;
}
impl Hash for usize {
    fn hash(&self) -> usize {
        *self % 10
    }
}
impl Hash for String {
    fn hash(&self) -> usize {
        self.len() % 24
    }
}

fn foo(x: impl Hash) {
    println!("hash is {}", x.hash());
}

fn main() {
    foo(32usize);
}