}
  }

  @Override
  final Iterator<E> elementIterator() {
    return new Itr<E>() {
      @Override
      @ParametricNullness
      E result(int entryIndex) {
        return backingMap.getKey(entryIndex);
      }
    };
  }

  @Override
  final Iterator<Entry<E>> entryIterator() {
    return new Itr<Entry<E>>() {
      @Override
      Entry<E> result(int entryIndex) {

    }

    // test that the RangeSet's span is the span of all the ranges
    Iterator<Range<C>> itr = rangeSet.asRanges().iterator();
    Range<C> expectedSpan = null;
    if (itr.hasNext()) {
      expectedSpan = itr.next();
      while (itr.hasNext()) {
        expectedSpan = expectedSpan.span(itr.next());
      }
    }

    try {
      Range<C> span = rangeSet.span();
      assertEquals(expectedSpan, span);

      collection.clear();
      totalSize -= count;
    }
  }

  private abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
    final Iterator<Entry<K, Collection<V>>> keyIterator;
    @Nullable K key;
    @Nullable Collection<V> collection;
    Iterator<V> valueIterator;

    Itr() {
      keyIterator = map.entrySet().iterator();
      key = null;
      collection = null;

    assertEquals(ImmutableList.of(-1, 3, 5), result);
  }

  public void testLeastOfIterator_simple_nMinusOne_withNullElement() {
    Iterator<@Nullable Integer> itr = Iterators.forArray(3, null, 5, -1);
    List<@Nullable Integer> result = Ordering.<Integer>natural().nullsLast().leastOf(itr, 3);
    assertTrue(result instanceof RandomAccess);
    assertListImmutable(result);
    assertEquals(ImmutableList.of(-1, 3, 5), result);
  }

    assertEquals(ImmutableList.of(-1, 3, 5), result);
  }

  public void testLeastOfIterator_simple_nMinusOne_withNullElement() {
    Iterator<@Nullable Integer> itr = Iterators.forArray(3, null, 5, -1);
    List<@Nullable Integer> result = Ordering.<Integer>natural().nullsLast().leastOf(itr, 3);
    assertTrue(result instanceof RandomAccess);
    assertListImmutable(result);
    assertEquals(ImmutableList.of(-1, 3, 5), result);
  }