* {@linkplain Cache#invalidate invalidations}.
   */
  public long evictionCount() {
    return evictionCount;
  }

  /**
   * Returns a new {@code CacheStats} representing the difference between this {@code CacheStats}
   * and {@code other}. Negative values, which aren't supported by {@code CacheStats} will be
   * rounded up to zero.
   */
  public CacheStats minus(CacheStats other) {

      SortedMap<K, ? extends V> sortedLeft = (SortedMap<K, ? extends V>) left;
      return difference(sortedLeft, right);
    }
    return difference(left, right, Equivalence.equals());
  }

  /**
   * Computes the difference between two maps. This difference is an immutable snapshot of the state
   * of the maps at the time this method is called. It will never change, even if the maps change at
   * a later time.
   *

  private static final double ALLOWED_ERROR = 1.0e-10;
  private static final QuantilesAlgorithm REFERENCE_ALGORITHM = QuantilesAlgorithm.SORTING;
  private static final Set<QuantilesAlgorithm> NON_REFERENCE_ALGORITHMS =
      Sets.difference(
          ImmutableSet.copyOf(QuantilesAlgorithm.values()), ImmutableSet.of(REFERENCE_ALGORITHM));

  private double[] dataset;

  @Override
  protected void setUp() {
    dataset = new double[DATASET_SIZE];

          .put(Ordering.class, AlwaysEqual.INSTANCE)
          .put(Range.class, Range.all())
          .put(MapDifference.class, Maps.difference(ImmutableMap.of(), ImmutableMap.of()))
          .put(
              SortedMapDifference.class,
              Maps.difference(ImmutableSortedMap.of(), ImmutableSortedMap.of()))
          // reflect
          .put(AnnotatedElement.class, Object.class)

          .put(Ordering.class, AlwaysEqual.INSTANCE)
          .put(Range.class, Range.all())
          .put(MapDifference.class, Maps.difference(ImmutableMap.of(), ImmutableMap.of()))
          .put(
              SortedMapDifference.class,
              Maps.difference(ImmutableSortedMap.of(), ImmutableSortedMap.of()))
          // reflect
          .put(AnnotatedElement.class, Object.class)

 *
 * @author Mike Bostock
 */
public class SynchronizedSetTest extends TestCase {

  public static final Object MUTEX = new Integer(1); // something Serializable

  // TODO(cpovirk): Resolve difference between branches in their choice of mutex:
  // - The mainline uses `null` (even since the change in cl/99720576 was integrated).
  // - The backport continued to use MUTEX.
  public static Test suite() {

  }

  /**
   * Returns a new range set consisting of the difference of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).removeAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> difference(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);

  }

  /**
   * Returns a new range set consisting of the difference of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).removeAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> difference(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);

            .add(Range.openClosed(3, 4))
            .add(Range.open(8, 10))
            .add(Range.openClosed(15, 17))
            .build();

    assertThat(RANGE_SET_ONE.difference(RANGE_SET_TWO)).isEqualTo(expected);
  }

  public void testAsSet() {
    ImmutableSortedSet<Integer> expectedSet = ImmutableSortedSet.of(2, 3, 4, 8, 9, 16, 17);

                      Iterators.transform(
                          // filter out 'node' from successors (already covered by predecessors,
                          // above)
                          Sets.difference(graph.successors(node), ImmutableSet.of(node)).iterator(),
                          (N successor) -> EndpointPair.ordered(node, successor))));
            } else {
              return Iterators.unmodifiableIterator(