fn d(n int) f64 {
    return f64(n)
}

fn e(n int) {}

fn f(n int) ?f64 {
    return f64(n)
}

fn g(n int) ? {}

fn main() {
    tg := [
        spawn d(0),
        spawn d(1),
    ]
    r := tg.wait()?
    println(r)
    s := tg[0].wait() or { panic('problem') }
    println(s)
    tg2 := [
        spawn e(0),
        spawn e(1),
    ]
    tg2.wait() or { panic('problem') }
    tg2[0].wait()?
    tg3 := [
        spawn f(0),
        spawn f(1),
    ]
    tg3.wait() or { panic('problem') }
    for t in tg3 {
        a := t.wait()
        println(a)
    }
    for i, _ in tg3 {
        a := tg3[i].wait()
        println(a)
    }
    tg4 := [
        spawn g(0),
        spawn g(1),
    ]
    tg4.wait()
    tg4[0].wait()
    spawn g(3) or { panic('problem') }
}