public void testPowerSetEquals_independentOfOrder() {
    ImmutableSet<Integer> elements = ImmutableSet.of(1, 2, 3, 4);
    Set<Set<Integer>> forward = powerSet(elements);
    Set<Set<Integer>> reverse = powerSet(ImmutableSet.copyOf(elements.asList().reverse()));
    new EqualsTester().addEqualityGroup(forward, reverse).testEquals();
  }

  /**
   * Test that a hash code miscomputed by "input.hashCode() * tooFarValue / 2" is correct under our