private static void intersectTo(@NotNull IntSet small, @NotNull IntSet big, @NotNull IntSet result) {
    for (IntIterator iterator = small.iterator(); iterator.hasNext(); ) {
      int value = iterator.nextInt();
      if (big.contains(value)) {
        result.add(value);
      }
    }
  }
private static void intersectTo(@NotNull IntSet small, @NotNull IntSet big, @NotNull IntSet result)