* elements of each iterator in {@code inputs}. The input iterators are not polled until
   * necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it. The methods of the returned iterator may throw {@code NullPointerException} if any
   * of the input iterators is null.
   */

   * elements of each iterator in {@code inputs}. The input iterators are not polled until
   * necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it. The methods of the returned iterator may throw {@code NullPointerException} if any
   * of the input iterators is null.
   */

    assertNextThrows(iterator);

    /* Checks the case where a later element throws an exception. */

    list = Lists.newArrayList(1, 2);
    iterator = peekingIterator(new ThrowsAtEndIterator<Integer>(list));
    assertTrue(iterator.hasNext());
    iterator.next();
    assertTrue(iterator.hasNext());
    iterator.next();
    assertNextThrows(iterator);
  }

  private void assertNextThrows(Iterator<?> iterator) {

  public void testSize0() {
    Iterator<String> iterator = Iterators.emptyIterator();
    assertEquals(0, Iterators.size(iterator));
  }

  public void testSize1() {
    Iterator<Integer> iterator = Collections.singleton(0).iterator();
    assertEquals(1, Iterators.size(iterator));
  }

  public void testSize_partiallyConsumed() {
    Iterator<Integer> iterator = asList(1, 2, 3, 4, 5).iterator();
    iterator.next();

      checkNotNull(c);
      boolean changed = false;
      Iterator<Map<C, V>> iterator = backingMap.values().iterator();
      while (iterator.hasNext()) {
        Map<C, V> map = iterator.next();
        // map.keySet().removeAll(c) can throw a NPE when map is a TreeMap with
        // natural ordering and c contains a null.
        if (Iterators.removeAll(map.keySet().iterator(), c)) {
          changed = true;

    assertNextThrows(iterator);

    /* Checks the case where a later element throws an exception. */

    list = Lists.newArrayList(1, 2);
    iterator = peekingIterator(new ThrowsAtEndIterator<Integer>(list));
    assertTrue(iterator.hasNext());
    iterator.next();
    assertTrue(iterator.hasNext());
    iterator.next();
    assertNextThrows(iterator);
  }

  private void assertNextThrows(Iterator<?> iterator) {

    Iterator<E> iterator = iterator();
    while (iterator.hasNext()) {
      if (Objects.equal(iterator.next(), object)) {
        iterator.remove();
        return true;
      }
    }
    return false;
  }

  /**
   * A sensible definition of {@link #removeAll} in terms of {@link #iterator}, using the iterator's

      @Override
      public Iterator<T> iterator() {
        return Iterators.concat(
            /* lazily generate the iterators on each input only as needed */
            new AbstractIndexedListIterator<Iterator<? extends T>>(inputs.length) {
              @Override
              public Iterator<? extends T> get(int i) {
                return inputs[i].iterator();
              }
            });
      }

     */
    public MultiIterator(final Iterator<E>... iterators) {
        assertArgumentNotNull("iterators", iterators);
        this.iterators = iterators;
    }

    @Override
    public boolean hasNext() {
        for (; index < iterators.length; ++index) {
            if (iterators[index].hasNext()) {
                return true;
            }
        }
        return false;
    }

      }

      @Override
      Iterator<E> elementIterator() {
        throw new AssertionError("should never be called");
      }

      @Override
      Iterator<Entry<E>> entryIterator() {
        final Iterator<? extends Entry<? extends E>> iterator1 = multiset1.entrySet().iterator();
        final Iterator<? extends Entry<? extends E>> iterator2 = multiset2.entrySet().iterator();