* com.google.common.collect.Ordering#lexicographical} does for orderings.
   *
   * <p>The returned object is serializable if this object is serializable.
   *
   * @since 10.0
   */
  @GwtCompatible(serializable = true)
  public final <S extends @Nullable T> Equivalence<Iterable<S>> pairwise() {
    // Ideally, the returned equivalence would support Iterable<? extends T>. However,

  @GwtCompatible(serializable = true)
  public <S extends T> Ordering<S> reverse() {
    return new ReverseOrdering<>(this);
  }

  /**
   * Returns an ordering that treats {@code null} as less than all other values and uses {@code
   * this} to compare non-null values.
   *
   * <p>The returned object is serializable if this object is serializable.
   *

   * operation throws an {@link UnsupportedOperationException}.
   *
   * <p>The returned entry is serializable.
   *
   * <p><b>Java 9 users:</b> consider using {@code java.util.Map.entry(key, value)} if the key and
   * value are non-null and the entry does not need to be serializable.
   *
   * @param key the key to be associated with the returned entry