Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");

    Set<String> goodFriends = Sets.difference(friends, enemies);
    assertEquals(2, goodFriends.size());

    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());

    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "b");
  }

  public void testDifferenceWithRemovedElement() {
    Multiset<String> ms1 = HashMultiset.create(Arrays.asList("a", "b", "a"));
    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("b"));
    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "a");
  }

    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");

    Set<String> goodFriends = Sets.difference(friends, enemies);
    assertEquals(2, goodFriends.size());

    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());

  }

  public void testOneSecondBurst() {
    RateLimiter limiter = RateLimiter.create(5.0, stopwatch);
    stopwatch.sleepMillis(1000); // max capacity reached
    stopwatch.sleepMillis(1000); // this makes no difference
    limiter.acquire(1); // R0.00, since it's the first request

    limiter.acquire(1); // R0.00, from capacity
    limiter.acquire(3); // R0.00, from capacity

    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "b");
  }

  public void testDifferenceWithRemovedElement() {
    Multiset<String> ms1 = HashMultiset.create(Arrays.asList("a", "b", "a"));
    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("b"));
    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "a");
  }

  }

  public void testOneSecondBurst() {
    RateLimiter limiter = RateLimiter.create(5.0, stopwatch);
    stopwatch.sleepMillis(1000); // max capacity reached
    stopwatch.sleepMillis(1000); // this makes no difference
    limiter.acquire(1); // R0.00, since it's the first request

    limiter.acquire(1); // R0.00, from capacity
    limiter.acquire(3); // R0.00, from capacity

   */
  public static int checkedAdd(int a, int b) {
    long result = (long) a + b;
    checkNoOverflow(result == (int) result, "checkedAdd", a, b);
    return (int) result;
  }

  /**
   * Returns the difference of {@code a} and {@code b}, provided it does not overflow.
   *
   * @throws ArithmeticException if {@code a - b} overflows in signed {@code int} arithmetic
   */
  public static int checkedSubtract(int a, int b) {

   * {@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) {

   * {@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) {

          .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)