*/
  @CheckForNull
  protected Entry<E> standardPollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }
    Entry<E> entry = entryIterator.next();
    entry = Multisets.immutableEntry(entry.getElement(), entry.getCount());
    entryIterator.remove();
    return entry;
  }

  @Override
  @CheckForNull

  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));

    // Avoiding ConcurrentModificationExceptions is tricky.
    Iterator<Entry<E>> entryIterator = multisetToModify.entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<E> entry = entryIterator.next();
      int retainCount = occurrencesToRetain.count(entry.getElement());
      if (retainCount == 0) {
        entryIterator.remove();
        changed = true;

    // Avoiding ConcurrentModificationExceptions is tricky.
    Iterator<Entry<E>> entryIterator = multisetToModify.entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<E> entry = entryIterator.next();
      int retainCount = occurrencesToRetain.count(entry.getElement());
      if (retainCount == 0) {
        entryIterator.remove();
        changed = true;

  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));

      lastEntry = null;
    }
  }

  /** KeyIterator build on top of EntryIterator. */
  final class KeyIterator implements Iterator<K> {
    private EntryIterator iterator;

    KeyIterator() {
      iterator = new EntryIterator();
    }

    @Override
    public boolean hasNext() {
      return iterator.hasNext();
    }

    @Override

    final Iterator<Map.Entry<E, Count>> entryIterator;
    @CheckForNull Map.Entry<E, Count> currentEntry;
    int occurrencesLeft;
    boolean canRemove;

    MapBasedMultisetIterator() {
      this.entryIterator = backingMap.entrySet().iterator();
    }

    @Override
    public boolean hasNext() {
      return occurrencesLeft > 0 || entryIterator.hasNext();
    }

    @Override

    Iterator<Entry<String, Integer>> entryIterator = multimap.entries().iterator();
    assertEquals(immutableEntry("foo", 5), entryIterator.next());
    assertEquals(immutableEntry("bar", 4), entryIterator.next());
    assertEquals(immutableEntry("foo", 3), entryIterator.next());
    assertEquals(immutableEntry("cow", 2), entryIterator.next());
    assertEquals(immutableEntry("bar", 1), entryIterator.next());

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

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

      return frequency;
    }

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

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