/**
   * A sensible definition of {@link #lowerEntry} in terms of the {@code lastEntry()} of {@link
   * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
   * lowerEntry} to forward to this implementation.
   */
  protected @Nullable Entry<K, V> standardLowerEntry(@ParametricNullness K key) {
    return headMap(key, false).lastEntry();
  }

  @Override

  /**
   * A sensible definition of {@link #lowerEntry} in terms of the {@code lastEntry()} of {@link
   * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
   * lowerEntry} to forward to this implementation.
   */
  protected @Nullable Entry<K, V> standardLowerEntry(@ParametricNullness K key) {
    return headMap(key, false).lastEntry();
  }

  @Override

    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {
    return headMap(toKey, false);
  }

  @Override
  public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
    return new SafeTreeMap<>(delegate.headMap(checkValid(toKey), inclusive));
  }

  @Override
  public @Nullable Entry<K, V> higherEntry(K key) {

      extends AbstractNavigableMap<Cut<C>, Range<C>> {
    private final NavigableMap<Cut<C>, Range<C>> rangesByLowerBound;

    /**
     * upperBoundWindow represents the headMap/subMap/tailMap view of the entire "ranges by upper
     * bound" map; it's a constraint on the *keys*, and does not affect the values.
     */
    private final Range<Cut<C>> upperBoundWindow;

    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {
    return headMap(toKey, false);
  }

  @Override
  public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
    return new SafeTreeMap<>(delegate.headMap(checkValid(toKey), inclusive));
  }

  @Override
  public @Nullable Entry<K, V> higherEntry(K key) {

        return tmp;
      }
    }
    return null;
  }

  @Override
  public ImmutableSortedMap<K, V> headMap(K toKey) {
    checkNotNull(toKey);
    return newView(sortedDelegate.headMap(toKey));
  }

  ImmutableSortedMap<K, V> headMap(K toKey, boolean inclusive) {
    checkNotNull(toKey);
    if (inclusive) {
      K tmp = higher(toKey);
      if (tmp == null) {

    }

    @Override
    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
      return headMap(toKey, false);
    }

    @Override
    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey, boolean inclusive) {
      return new NavigableAsMap(sortedMap().headMap(toKey, inclusive));
    }

    @Override

    extends AbstractImmutableSortedMapMapInterfaceTest<String, Integer> {
  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("a", 1, "b", 2, "c", 3, "d", 4, "e", 5).headMap("c", true);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "d";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return 4;
  }

  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapExclusive() {
    assertFalse(navigableMap.headMap(a.getKey(), false).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapInclusive() {
    assertTrue(navigableMap.headMap(a.getKey(), true).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapExclusive() {

  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapExclusive() {
    assertFalse(navigableMap.headMap(a.getKey(), false).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testHeadMapInclusive() {
    assertTrue(navigableMap.headMap(a.getKey(), true).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapExclusive() {