`Well, there was Mystery,' the Mock Turtle replied, counting
off the subjects on his flappers, `--Mystery, ancient and modern,
with Seaography:  then Drawling--the Drawling-master was an old
conger-eel, that used to come once a week:  HE taught us
Drawling, Stretching, and Fainting in Coils.'

  `What was THAT like?' said Alice.

  `Well, I can't show it you myself,' the Mock Turtle said:  `I'm
too stiff.  And the Gryphon never learnt it.'

  @CollectionSize.Require(ZERO)
  public void testPeek_empty() {
    assertNull("emptyQueue.peek() should return null", getQueue().peek());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)

  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E remove() {
    return delegate().remove();
  }

  @Override
  @CheckForNull
  public E peek() {
    return delegate().peek();
  }

  @Override
  @ParametricNullness
  public E element() {
    return delegate().element();
  }

  /**

    public boolean remove(Object object) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove(object);
    }

    @Override
    public @Nullable E peek() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.peek();
    }

    @Override
    public E element() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.element();
    }

    @Override

import com.google.common.annotations.J2ktIncompatible;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import javax.annotation.CheckForNull;

/**
 * Weak reference with a {@code finalizeReferent()} method which a background thread invokes after
 * the garbage collector reclaims the referent. This is a simpler alternative to using a {@link
 * ReferenceQueue}.
 *
 * @author Bob Lee

    // Using @Weak is necessary to avoid retain-cycles between BiEntry instances on iOS,
    // which would cause memory leaks when non-empty HashBiMap with cyclic BiEntry
    // instances is deallocated.
    @CheckForNull BiEntry<K, V> nextInKToVBucket;
    @Weak @CheckForNull BiEntry<K, V> nextInVToKBucket;

    @Weak @CheckForNull BiEntry<K, V> nextInKeyInsertionOrder;

          .put("concurrencyLevel", new ConcurrencyLevelParser())
          .put("weakKeys", new KeyStrengthParser(Strength.WEAK))
          .put("softValues", new ValueStrengthParser(Strength.SOFT))
          .put("weakValues", new ValueStrengthParser(Strength.WEAK))
          .put("recordStats", new RecordStatsParser())
          .put("expireAfterAccess", new AccessDurationParser())

        }
      };

  private CacheBuilderFactory factoryWithAllKeyStrengths() {
    return new CacheBuilderFactory()
        .withKeyStrengths(ImmutableSet.of(STRONG, Strength.WEAK))
        .withValueStrengths(ImmutableSet.of(STRONG, Strength.WEAK, Strength.SOFT));
  }

  private Iterable<LoadingCache<Key, String>> caches() {
    CacheBuilderFactory factory = factoryWithAllKeyStrengths();
    return Iterables.transform(

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertThat(map.entryHelper)
        .isInstanceOf(MapMakerInternalMap.WeakKeyStrongValueEntry.Helper.class);
  }

  public void testSetWeakValues() {
    MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(createMapMaker().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertThat(map.entryHelper)

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertThat(map.entryHelper)
        .isInstanceOf(MapMakerInternalMap.WeakKeyStrongValueEntry.Helper.class);
  }

  public void testSetWeakValues() {
    MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(createMapMaker().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertThat(map.entryHelper)