use std::collections::HashMap;
use std::sync::Arc;

#[derive(PartialEq, Eq, Hash, Debug)]
struct V {}

fn main() {
    let v1 = V {};
    let v2 = V {};

    let mut collect = HashMap::<&V, usize>::new();

    collect.insert(&v1, 15);
    collect.insert(&v2, 42);

    println!("{:?}", collect.get(&v1));
}