}
  }

  private <T extends @Nullable Object> void actsLikeIteratorHelper(final List<T> list) {
    // Check with modifiable copies of the list
    new PeekingIteratorTester<T>(list).test();

    // Check with unmodifiable lists
    new IteratorTester<T>(
        list.size() * 2 + 2, UNMODIFIABLE, list, IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<T> newTargetIterator() {

    }
  }

  private <T extends @Nullable Object> void actsLikeIteratorHelper(final List<T> list) {
    // Check with modifiable copies of the list
    new PeekingIteratorTester<T>(list).test();

    // Check with unmodifiable lists
    new IteratorTester<T>(
        list.size() * 2 + 2, UNMODIFIABLE, list, IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<T> newTargetIterator() {

    assertUnmodifiableIterableInTandem(
        unmodifiable.asMap().entrySet(), multimap.asMap().entrySet());

    assertEquals(multimap.toString(), unmodifiable.toString());
    assertEquals(multimap.hashCode(), unmodifiable.hashCode());
    assertEquals(multimap, unmodifiable);

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);

    }
  }

  public void testSkip_allOfMutableList_modifiable() {
    List<String> list = newArrayList("a", "b");
    Iterator<String> iterator = skip(list, 2).iterator();
    try {
      iterator.remove();
      fail("Expected IllegalStateException");
    } catch (IllegalStateException expected) {
    }
  }

  public void testSkip_allOfImmutableList_modifiable() {
    List<String> list = ImmutableList.of("a", "b");

    protected EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    protected SingletonIteratorTester() {
      super(3, MODIFIABLE, singleton(1), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

    assertUnmodifiableIterableInTandem(
        unmodifiable.asMap().entrySet(), multimap.asMap().entrySet());

    assertEquals(multimap.toString(), unmodifiable.toString());
    assertEquals(multimap.hashCode(), unmodifiable.hashCode());
    assertEquals(multimap, unmodifiable);

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);

    }
  }

  public void testSkip_allOfMutableList_modifiable() {
    List<String> list = newArrayList("a", "b");
    Iterator<String> iterator = skip(list, 2).iterator();
    try {
      iterator.remove();
      fail("Expected IllegalStateException");
    } catch (IllegalStateException expected) {
    }
  }

  public void testSkip_allOfImmutableList_modifiable() {
    List<String> list = ImmutableList.of("a", "b");

    protected EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    protected SingletonIteratorTester() {
      super(3, MODIFIABLE, singleton(1), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

 * value and the old value.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned
 * views are modifiable.
 *
 * <p>The lists returned by {@link #get}, {@link #removeAll}, and {@link #replaceValues} all
 * implement {@link java.util.RandomAccess}.
 *

 *
 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
 * support them). All optional multimap methods are supported, and all returned views are
 * modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly. To allow concurrent update operations, wrap your multimap