static ItIt<Pair<S, Int>> returnCodesOfMultipleServers_iterator(S... servers) {
  ret returnCodesOfMultipleServers_iterator(asList(servers));
}

static ItIt<Pair<S, Int>> returnCodesOfMultipleServers_iterator(Iterable<S> servers) {
  ret (ItIt) map_iterator_asPair(f returnCodeHttpHEAD, servers);
}