import java.util.Set;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
 * {@code entryIterator()}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
    implements SortedMultiset<E> {

    @Nullable Entry<K, Collection<V>> pollAsMapEntry(
        Iterator<Entry<K, Collection<V>>> entryIterator) {
      if (!entryIterator.hasNext()) {
        return null;
      }
      Entry<K, Collection<V>> entry = entryIterator.next();
      Collection<V> output = createCollection();
      output.addAll(entry.getValue());
      entryIterator.remove();
      return immutableEntry(entry.getKey(), unmodifiableCollectionSubclass(output));

        Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();

        return new UnmodifiableIterator<K>() {
          @Override
          public boolean hasNext() {
            return entryIterator.hasNext();
          }

          @Override
          public K next() {
            Entry<K, V> entry = entryIterator.next(); // store local reference for thread-safety

        }
      }
      return null;
    }

    @Override
    public int size() {
      return entriesByLowerBound.size();
    }

    @Override
    Iterator<Entry<Range<K>, V>> entryIterator() {
      return entryIterable.iterator();
    }
  }

  @Override
  public RangeMap<K, V> subRangeMap(Range<K> subRange) {
    if (subRange.equals(Range.all())) {
      return this;
    } else {

   */
  protected @Nullable V standardRemove(@Nullable Object key) {
    Iterator<Entry<K, V>> entryIterator = entrySet().iterator();
    while (entryIterator.hasNext()) {
      Entry<K, V> entry = entryIterator.next();
      if (Objects.equals(entry.getKey(), key)) {
        V value = entry.getValue();
        entryIterator.remove();
        return value;
      }
    }
    return null;
  }

  /**

    @Override
    Multimap<K, V> multimap() {
      return AbstractMultimap.this;
    }

    @Override
    public Iterator<Entry<K, V>> iterator() {
      return entryIterator();
    }
  }

  @WeakOuter
  final class EntrySet extends Entries implements Set<Entry<K, V>> {
    @Override
    public int hashCode() {
      return Sets.hashCodeImpl(this);
    }

      return frequency;
    }

    @Override
    Iterator<E> elementIterator() {
      return Multisets.elementIterator(entryIterator());
    }

    @Override
    Iterator<Entry<E>> entryIterator() {
      Iterator<Map.Entry<E, Integer>> backingEntries = backingMap.entrySet().iterator();
      return new UnmodifiableIterator<Multiset.Entry<E>>() {
        @Override

    Entry<String, String> firstEntry = entries.iterator().next();
    entries.remove(firstEntry);
    assertFalse(underlying.containsKey("f"));

    Iterator<Entry<String, String>> entryIterator = entries.iterator();
    entryIterator.next();
    entryIterator.remove();
    assertFalse(underlying.containsKey("g"));

    assertTrue(underlying.isEmpty());
    assertTrue(map.isEmpty());
    assertTrue(keys.isEmpty());

  UnmodifiableIterator<K> keyIterator() {
    UnmodifiableIterator<Entry<K, V>> entryIterator = entrySet().iterator();
    return new UnmodifiableIterator<K>() {
      @Override
      public boolean hasNext() {
        return entryIterator.hasNext();
      }

      @Override
      public K next() {
        return entryIterator.next().getKey();
      }
    };
  }

  UnmodifiableIterator<K> keyIterator() {
    UnmodifiableIterator<Entry<K, V>> entryIterator = entrySet().iterator();
    return new UnmodifiableIterator<K>() {
      @Override
      public boolean hasNext() {
        return entryIterator.hasNext();
      }

      @Override
      public K next() {
        return entryIterator.next().getKey();
      }
    };
  }