create a range with a custom function

range.rs

fn range(start: isize, stop: isize, fun : impl Fn(&isize) -> isize) -> Vec<isize> {
    let mut v = vec![start];
    let mut temp = start;

    loop {
        temp = fun(&temp);
        v.push(temp.clone());
        if temp < stop {
            break;
        }
    }
    v
}