Integers as keys of a HashMap

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examples/hashes/integers-as-keys/src/main.rs

use std::collections::HashMap;

fn main() {
    let mut lookup = HashMap::new();
    lookup.insert(0, "Sunday");
    lookup.insert(1, "Monday");
    lookup.insert(2, "Tuesday");

    println!("{:?}", lookup);
}

{0: "Sunday", 1: "Monday", 2: "Tuesday"}