static SS zipTwoListsToCIMap_strict_withoutEquals(LS l1, LS l2) {
  int n = l(l1);
  if (n != l(l2)) null;
  SS map = ciMap();
  for i to n:
    if (!strictPutICIfKeyNotEqualToValue(map, l1.get(i), l2.get(i)))
      null;
  ret map;
}