static PrimitiveIterator.OfInt filterTranslate(int arrayLength, IntPredicate filter, IntUnaryOperator translator) {
    return new IndexIterator(0, arrayLength, filter, translator);
  }
@Test
  public void testFilterTranslate() {
    assertEquals(IndexIterator.filterTranslate(20, value -> value < 5, Math::negateExact), 0, -1, -2, -3, -4);
  }