static <A, B extends Iterable<A>> ItIt<L<A>> outerProduct_arrays(B[] lists) {
  int n = l(lists);
  if (n == 0) ret emptyIterator();
  Class type = arrayElementType(lists);
  ret mapI(sll -> simplyLinkedListToArray(n, type, sll), outerProduct_faster(arrayToSimplyLinkedList(lists)));
}