assertNextPermutation(newArrayList(3, 4, 1, 2), permutations);
    assertNextPermutation(newArrayList(4, 3, 1, 2), permutations);

    assertNextPermutation(newArrayList(4, 3, 2, 1), permutations);
    assertNextPermutation(newArrayList(3, 4, 2, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 4, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 1, 4), permutations);

  }

  private static void assertReverseView(List<Integer> fromList, List<Integer> toList) {
    /* fromList modifications reflected in toList */
    fromList.set(0, 5);
    assertEquals(asList(4, 3, 2, 5), toList);
    fromList.add(6);
    assertEquals(asList(6, 4, 3, 2, 5), toList);
    fromList.add(2, 9);
    assertEquals(asList(6, 4, 3, 9, 2, 5), toList);
    fromList.remove(Integer.valueOf(2));

              | (1L << (23 - 2))
              | (1L << (29 - 2))
              | (1L << (31 - 2))
              | (1L << (37 - 2))
              | (1L << (41 - 2))
              | (1L << (43 - 2))
              | (1L << (47 - 2))
              | (1L << (53 - 2))
              | (1L << (59 - 2))
              | (1L << (61 - 2));
      // Look up n within the mask.