type MyFn = fn ()

struct Iter {
    f MyFn = fn () {}
mut:
    done bool
}

fn (mut it Iter) next() ?&MyFn {
    if it.done {
        return none
    }
    it.done = true
    return &it.f
}

fn test_main() {
    mut c := 0
    for p in Iter{} {
        println(p)
        w := *p
        w()
        c += 1
    }
    assert c == 1
}