#[derive(Debug, Copy, Clone)]

struct I(u64);

fn main() {
    let v: Vec<_> = (1..=3).map(|i| I(i)).collect();
    println!("{:?}", v[2]);

    let a: [_; 3] = [I(1), I(2), I(3)];
    println!("{:?}", a[2]);

    let mut a: [_; 3] = [I(1); 3];
    a.iter_mut().enumerate().for_each(|(i, e)| *e = I(i as u64 + 1));
    println!("{:?}", a[2]);
}