#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::collections::VecDeque;
fn main() {
    let a = [1, 2, 3];
    let doubled: VecDeque<i32> = a.iter().map(|x| x * 2).collect();
    assert_eq!(2, doubled[0]);
    assert_eq!(4, doubled[1]);
    assert_eq!(6, doubled[2]);
}