*
   * @param multiset the presumed-immutable multiset
   * @param sampleElement an element of the same type as that contained by {@code multiset}. {@code
   *     multiset} may or may not have {@code sampleElement} as a member.
   */
  public static <E extends @Nullable Object> void assertMultisetIsUnmodifiable(
      Multiset<E> multiset, E sampleElement) {
    Multiset<E> copy = LinkedHashMultiset.create(multiset);

    multiset.add(s1);
    multiset.add(s2, 3);
    assertEquals(2, multiset.count(s1));
    assertEquals(3, multiset.count(s2));

    multiset.remove(s1);
    assertEquals(1, multiset.count(s1));
    assertEquals(3, multiset.count(s2));
  }

  public void testLogicalKeyEquality_strongKeys() {
    testLogicalKeyEquality(STRONG);
  }

  public void testLogicalKeyEquality_weakKeys() {

    multiset.add("foo", 2);
    multiset.add("bar");
    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));
    assertEquals("[foo x 2, bar]", multiset.toString());
  }

  public void testCreateFromIterable() {
    Multiset<String> multiset = TreeMultiset.create(Arrays.asList("foo", "bar", "foo"));
    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));

        .testForwarding(
            Multiset.class,
            new Function<Multiset, Multiset>() {
              @Override
              public Multiset apply(Multiset delegate) {
                return wrap(delegate);
              }
            });
  }

  public void testEquals() {
    Multiset<String> set1 = ImmutableMultiset.of("one");
    Multiset<String> set2 = ImmutableMultiset.of("two");

    }
  }

  public void testCopyOf_multiset_empty() {
    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);

  }

  // Required Implementations

  /**
   * {@inheritDoc}
   *
   * <p>Invoking {@link Multiset.Entry#getCount} on an entry in the returned set always returns the
   * current count of that element in the multiset, as opposed to the count at the time the entry
   * was retrieved.
   */
  @Override
  public Set<Multiset.Entry<E>> entrySet() {
    return super.entrySet();
  }

  @Override
  Iterator<E> elementIterator() {

   *
   * @param multiset the presumed-immutable multiset
   * @param sampleElement an element of the same type as that contained by {@code multiset}. {@code
   *     multiset} may or may not have {@code sampleElement} as a member.
   */
  public static <E extends @Nullable Object> void assertMultisetIsUnmodifiable(
      Multiset<E> multiset, E sampleElement) {
    Multiset<E> copy = LinkedHashMultiset.create(multiset);

   */
  protected class StandardElementSet extends Multisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {}

    @Override
    Multiset<E> multiset() {
      return ForwardingMultiset.this;
    }

    @Override
    public Iterator<E> iterator() {
      return Multisets.elementIterator(multiset().entrySet().iterator());
    }
  }

  /**

   */
  protected class StandardElementSet extends Multisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {}

    @Override
    Multiset<E> multiset() {
      return ForwardingMultiset.this;
    }

    @Override
    public Iterator<E> iterator() {
      return Multisets.elementIterator(multiset().entrySet().iterator());
    }
  }

  /**

  }

  public void testEmptyRangeSubMultiset(SortedMultiset<E> multiset) {
    assertTrue(multiset.isEmpty());
    assertEquals(0, multiset.size());
    assertEquals(0, multiset.toArray().length);
    assertTrue(multiset.entrySet().isEmpty());
    assertFalse(multiset.iterator().hasNext());
    assertEquals(0, multiset.entrySet().size());
    assertEquals(0, multiset.entrySet().toArray().length);