generics

use std::marker::PhantomData;

struct Token<'a> {
    _marker: PhantomData<&'a ()>,
}

trait Container {
    type Item;
    fn get(&self, index: usize) -> Option<&Self::Item>;
}

struct Warehouse {

use std::fmt::Display;

fn print_it<T: Display>(value: T) {
    println!("Value: {}", value);
}