Iterator::skip: method(n) {
    n.times { this { break; } }
}
Iterator::window: method(start, length) {
    this.skip(start);
    return this.take(length);
}

only_uniq: fun(arr) fiber {
    len: arr.length;
    iters: range(0, len).map(|i| arr.cycle.window(i, len).to_a);
    iters {|it,rest|
        if (rest.select(|e| e == it).to_a.empty) {
            yield it;
        }
    }
}

only_uniq([3, 1, 4, 1, 5, 9, 2, 6, 5]).to_a.p;