return new SortedMultisets.ElementSet<E>(this);
  }

  @Override
  public Comparator<? super E> comparator() {
    return comparator;
  }

  @Override
  @CheckForNull
  public Entry<E> firstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  @CheckForNull
  public Entry<E> lastEntry() {

        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {
      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {

              });
          // requireNonNull is safe because the first `size` elements have been filled in.
          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
          K prevKey = firstEntry.getKey();
          keys[0] = prevKey;
          values[0] = firstEntry.getValue();
          checkEntryNotNull(keys[0], values[0]);
          for (int i = 1; i < size; i++) {

      return standardHigherEntry(key);
    }

    @Override
    public @Nullable K higherKey(K key) {
      return standardHigherKey(key);
    }

    @Override
    public @Nullable Entry<K, V> firstEntry() {
      return standardFirstEntry();
    }

    /*
     * We can't override lastEntry to delegate to standardLastEntry, as it would create an infinite

    return new SortedMultisets.NavigableElementSet<>(this);
  }

  @Override
  public Comparator<? super E> comparator() {
    return comparator;
  }

  @Override
  @CheckForNull
  public Entry<E> firstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  @CheckForNull
  public Entry<E> lastEntry() {

        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {
      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {

      return standardHigherEntry(key);
    }

    @Override
    public @Nullable K higherKey(K key) {
      return standardHigherKey(key);
    }

    @Override
    public @Nullable Entry<K, V> firstEntry() {
      return standardFirstEntry();
    }

    /*
     * We can't override lastEntry to delegate to standardLastEntry, as it would create an infinite

              });
          // requireNonNull is safe because the first `size` elements have been filled in.
          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
          K prevKey = firstEntry.getKey();
          keys[0] = prevKey;
          values[0] = firstEntry.getValue();
          checkEntryNotNull(keys[0], values[0]);
          for (int i = 1; i < size; i++) {

   */
  @Override
  Comparator<? super E> comparator();

  /**
   * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @CheckForNull
  Entry<E> firstEntry();

  /**
   * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @CheckForNull
  Entry<E> lastEntry();

  /**

    public K higherKey(@ParametricNullness K key) {
      return sortedMap().higherKey(key);
    }

    @Override
    @CheckForNull
    public Entry<K, Collection<V>> firstEntry() {
      Entry<K, Collection<V>> entry = sortedMap().firstEntry();
      return (entry == null) ? null : wrapEntry(entry);
    }

    @Override
    @CheckForNull
    public Entry<K, Collection<V>> lastEntry() {