public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

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

        @Override
        public boolean retainAll(Collection<?> c) {
          return delegate.keySet().retainAll(c);
        }
      };
    }

        public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

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

        @Override
        public boolean retainAll(Collection<?> c) {
          return delegate.keySet().retainAll(c);
        }
      };
    }

   * Iterables.frequency(occurrencesToRemove, e))}.
   *
   * <p>This is <i>not</i> the same as {@code multisetToModify.} {@link Multiset#removeAll
   * removeAll}{@code (occurrencesToRemove)}, which removes all occurrences of elements that appear
   * in {@code occurrencesToRemove}. However, this operation <i>is</i> equivalent to, albeit

    }
  }

  @Override
  public boolean containsKey(@CheckForNull Object key) {
    return asMap().get(key) != null;
  }

  @Override
  public Collection<V> removeAll(@CheckForNull Object key) {
    return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
  }

  Collection<V> unmodifiableEmptyCollection() {

   * collection's {@code add()} and {@code addAll()} methods throw an {@link
   * IllegalArgumentException}. When methods such as {@code removeAll()} and {@code clear()} are
   * called on the filtered collection, only elements that satisfy the filter will be removed from
   * the underlying collection.
   *

   *
   * <p>This is essentially the same as {@code
   * TreeRangeSet.create(this).removeAll(other.complement())} except it returns an {@code
   * ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> intersection(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);
    copy.removeAll(other.complement());
    return copyOf(copy);
  }

  /**

   *
   * <p>This is essentially the same as {@code
   * TreeRangeSet.create(this).removeAll(other.complement())} except it returns an {@code
   * ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> intersection(RangeSet<C> other) {
    RangeSet<C> copy = TreeRangeSet.create(this);
    copy.removeAll(other.complement());
    return copyOf(copy);
  }

  /**

  }

  public void testRemoveAll_collection() {
    List<String> list = newArrayList("a", "b", "c", "d", "e");
    assertTrue(Iterables.removeAll(list, newArrayList("b", "d", "f")));
    assertEquals(newArrayList("a", "c", "e"), list);
    assertFalse(Iterables.removeAll(list, newArrayList("x", "y", "z")));
    assertEquals(newArrayList("a", "c", "e"), list);
  }

  public void testRemoveAll_iterable() {

   * collection's {@code add()} and {@code addAll()} methods throw an {@link
   * IllegalArgumentException}. When methods such as {@code removeAll()} and {@code clear()} are
   * called on the filtered collection, only elements that satisfy the filter will be removed from
   * the underlying collection.
   *

    assertEquals(47, (int) mmHeap.pollLast());
    assertEquals(4, (int) mmHeap.pollLast());
    mmHeap.removeAll(Lists.newArrayList(2, 3));
    assertEquals(3, mmHeap.size());
    assertTrue("Heap is not intact after removeAll()", mmHeap.isIntact());
  }

  public void testContains() {
    MinMaxPriorityQueue<Integer> mmHeap = MinMaxPriorityQueue.create();