@Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    return delegate().pollLastEntry();
  }

  /**
   * A sensible definition of {@link #pollLastEntry()} in terms of {@code
   * descendingMultiset().entrySet().iterator()}.
   *
   * <p>If you override {@link #descendingMultiset()} or {@link #entrySet()}, you may wish to
   * override {@link #pollLastEntry()} to forward to this implementation.
   */

    }
    return result;
  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    return forwardMultiset().pollLastEntry();
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    return forwardMultiset().pollFirstEntry();
  }

  @Override
  public SortedMultiset<E> headMultiset(E toElement, BoundType boundType) {

    assertEquals(c, navigableMap.pollLastEntry());
    assertEquals(entries.subList(0, entries.size() - 1), copyToList(navigableMap.entrySet()));
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollLastUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> navigableMap.pollLastEntry());
  }

  @CollectionSize.Require(SEVERAL)

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    return delegate().pollLastEntry();
  }

  /**
   * A sensible definition of {@link #pollLastEntry()} in terms of {@code
   * descendingMultiset().entrySet().iterator()}.
   *
   * <p>If you override {@link #descendingMultiset()} or {@link #entrySet()}, you may wish to
   * override {@link #pollLastEntry()} to forward to this implementation.
   */

    }
    return result;
  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    return forwardMultiset().pollLastEntry();
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    return forwardMultiset().pollFirstEntry();
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E toElement, BoundType boundType) {

    }
    return result;
  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    return forwardMultiset().pollLastEntry();
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    return forwardMultiset().pollFirstEntry();
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E toElement, BoundType boundType) {

  }

  @Override
  public @Nullable Entry<K, V> pollFirstEntry() {
    return delegate.pollFirstEntry();
  }

  @Override
  public @Nullable Entry<K, V> pollLastEntry() {
    return delegate.pollLastEntry();
  }

  @Override
  public @Nullable V put(K key, V value) {
    return delegate.put(checkValid(key), value);
  }

  @Override

  }

  @Override
  public @Nullable Entry<K, V> pollFirstEntry() {
    return delegate.pollFirstEntry();
  }

  @Override
  public @Nullable Entry<K, V> pollLastEntry() {
    return delegate.pollLastEntry();
  }

  @Override
  public @Nullable V put(K key, V value) {
    return delegate.put(checkValid(key), value);
  }

  @Override

  }

  @Override
  @CheckForNull
  public Entry<K, V> pollFirstEntry() {
    return Iterators.pollNext(entryIterator());
  }

  @Override
  @CheckForNull
  public Entry<K, V> pollLastEntry() {
    return Iterators.pollNext(descendingEntryIterator());
  }

  @Override
  @ParametricNullness
  public K firstKey() {
    Entry<K, V> entry = firstEntry();
    if (entry == null) {

  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {