[Rust] Borrowing with modification demo

fn main() {
    let mut v = vec![1, 2, 3];

    // Modify vec in-place!
    square_each(&mut v);

    println!("{}", v[1]);
}

fn square_each(v: &mut Vec<i32>) {
    for e in v.iter_mut() {
        *e = (*e) * (*e);
    }
}