overload Deque[T](forward ...from: A) to: Deque[T] {
    initializeDequeMap(to, SizeT(countValues(...A)));

    var i = to.begin;
    try {
        static for (x in ...from) {
            i^ <-- x;
            inc(i);
        }
    } catch (ex) {
        destroyDequeValues(to.begin, i);
        destroyDequeMap(to);
        throw ex;
    }
}