fn main() {
    let vec: Vec<Result<i32, i32>> = vec![Ok(1), Err(2), Ok(1), Err(2)];

    let result: Result<Vec<i32>, i32> = vec.iter().cloned().collect();
    println!("collect res: {:?}", result);

    let (good, bad) = vec
        .iter()
        .cloned()
        .fold((vec![], vec![]), |(mut oks, mut errs), res| {
            match res {
                Ok(x) => oks.push(x),
                Err(e) => errs.push(e),
            };
            (oks, errs)
        });

    println!("fold: good {:?}, bad: {:?}", good, bad);
}