use std::collections::HashMap;
use std::hash::Hash;


trait Storable: Eq + Hash {
    fn do_nothing(&self) {}
}

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

impl Storable for ThingA {}

fn main() {

    let thing_a = ThingA{};
    let thing_b = ThingB{};

    let who_knows: &Storable = &thing_a;
    let no_work: Box<Storable> = Box::new(ThingA{});

    let db: HashMap<Box<Storable>, bool> = HashMap::new();

}