use std::collections::HashMap;
fn main() {
    let a = HashMap::from([("apple", 1), ("banana", 1)]);
    let b = HashMap::from([("apple", 2), ("peach", 2), ("grape", 2)]);

    let mut total: HashMap<&str, i32> = HashMap::new();
    total.extend(a);
    println!("{:#?}", total);

    total.extend(b);
    println!("{:#?}", total);
}
