if (hasNext()) {
        toRemove = iterator;
        return iterator.next();
      } else {
        throw new NoSuchElementException();
      }
    }

    @Override
    public void remove() {
      if (toRemove == null) {
        throw new IllegalStateException("no calls to next() since the last call to remove()");
      }
      toRemove.remove();
      toRemove = null;
    }

      if (hasNext()) {
        toRemove = iterator;
        return iterator.next();
      } else {
        throw new NoSuchElementException();
      }
    }

    @Override
    public void remove() {
      if (toRemove == null) {
        throw new IllegalStateException("no calls to next() since the last call to remove()");
      }
      toRemove.remove();
      toRemove = null;
    }

   * iteration over one of the multimap's collection views is in progress (except through the
   * iterator's own {@code remove} operation, or through the {@code setValue} operation on a map
   * entry returned by the iterator), the results of the iteration are undefined.
   *
   * <p>The multimap supports mapping removal, which removes the corresponding mapping from the map.

    taskFaker.runNextTask()
    assertThat(cache.remove("a")).isTrue()
    assertAbsent("a")
    cache.close()
    createNewCache()

    // The journal will have no record that 'a' was removed. It will have an entry for 'a', but when
    // it tries to read the cache files, it will find they were deleted. Once it encounters an entry
    // with missing cache files, it should remove it from the cache entirely.

    assertTrue(cycle.hasNext());
    try {
      cycle.remove();
      fail("no exception thrown");
    } catch (IllegalStateException expected) {
    }
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    try {
      cycle.remove();
      fail("no exception thrown");

    assertTrue(cycle.hasNext());
    try {
      cycle.remove();
      fail("no exception thrown");
    } catch (IllegalStateException expected) {
    }
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    try {
      cycle.remove();
      fail("no exception thrown");

                    int size = elements.length;
                    // Remove last element, if size > 1
                    Set<String> set1 =
                        (size > 1)
                            ? Sets.newHashSet(Arrays.asList(elements).subList(0, size - 1))
                            : Sets.newHashSet(elements);
                    // Remove first element, if size > 0
                    Set<String> set2 =

    }
  }

  @CheckForNull
  @CanIgnoreReturnValue
  @Override
  public V remove(@CheckForNull Object key) {
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).remove(key, hash);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
    if (key == null || value == null) {

    }

    @Override
    public Iterator<E> iterator() {
      return delegate().iterator(); // manually synchronized
    }

    @Override
    public boolean remove(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().remove(o);
      }
    }

    @Override
    public boolean removeAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().removeAll(c);

	if err == errNoSuchGroup {
		// group does not exist - so remove from memory.
		cache.removeGroupFromMembershipsMap(group)
		delete(cache.iamGroupsMap, group)
		cache.iamGroupPolicyMap.Delete(group)

		cache.updatedAt = time.Now()
		return nil
	}

	gi := cache.iamGroupsMap[group]

	// Updating the group memberships cache happens in two steps:
	//
	// 1. Remove the group from each user's list of memberships.