.test();
  }

  public void testPairwiseEquivalent_equals() {
    new EqualsTester()
        .addEqualityGroup(Equivalence.equals().pairwise(), Equivalence.equals().pairwise())
        .addEqualityGroup(Equivalence.identity().pairwise())
        .testEquals();
  }

  private enum LengthFunction implements Function<String, Integer> {
    INSTANCE;

    @Override
    public Integer apply(String input) {

    return false;
  }

  @Override
  public int hashCode() {
    return elementEquivalence.hashCode() ^ 0x46a3eb07;
  }

  @Override
  public String toString() {
    return elementEquivalence + ".pairwise()";
  }

  private static final long serialVersionUID = 1;

        .test();
  }

  public void testPairwiseEquivalent_equals() {
    new EqualsTester()
        .addEqualityGroup(Equivalence.equals().pairwise(), Equivalence.equals().pairwise())
        .addEqualityGroup(Equivalence.identity().pairwise())
        .testEquals();
  }

  private enum LengthFunction implements Function<String, Integer> {
    INSTANCE;

    @Override
    public Integer apply(String input) {

        Maps.toImmutableEnumMap(Entry::getKey, Entry::getValue);
    Equivalence<ImmutableMap<AnEnum, Integer>> equivalence =
        Equivalence.equals().<Entry<AnEnum, Integer>>pairwise().onResultOf(ImmutableMap::entrySet);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableMap.of(AnEnum.A, 1, AnEnum.C, 2, AnEnum.E, 3),
            mapEntry(AnEnum.A, 1),

    return false;
  }

  @Override
  public int hashCode() {
    return elementEquivalence.hashCode() ^ 0x46a3eb07;
  }

  @Override
  public String toString() {
    return elementEquivalence + ".pairwise()";
  }

  private static final long serialVersionUID = 1;

import java.util.Comparator;
import java.util.Iterator;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/** An ordering which sorts iterables by comparing corresponding elements pairwise. */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class LexicographicalOrdering<T extends @Nullable Object> extends Ordering<Iterable<T>>
    implements Serializable {

 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Comparators {
  private Comparators() {}

  /**
   * Returns a new comparator which sorts iterables by comparing corresponding elements pairwise
   * until a nonzero result is found; imposes "dictionary order." If the end of one iterable is
   * reached, but not the other, the shorter iterable is considered to be less than the longer one.

  static <C, E extends @Nullable Object, R extends Iterable<E>>
      BiPredicate<C, C> pairwiseOnResultOf(Function<C, R> arg) {
    Equivalence<C> equivalence = Equivalence.equals().<E>pairwise().onResultOf(arg);
    return equivalence::equivalent;
  }

        ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue);
    Equivalence<ImmutableMap<String, Integer>> equivalence =
        Equivalence.equals().<Entry<String, Integer>>pairwise().onResultOf(ImmutableMap::entrySet);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableMap.of("one", 1, "two", 2, "three", 3),
            mapEntry("one", 1),

            Comparator.naturalOrder(), Entry::getKey, Entry::getValue, Integer::sum);
    Equivalence<ImmutableMap<String, Integer>> equivalence =
        Equivalence.equals().<Entry<String, Integer>>pairwise().onResultOf(ImmutableMap::entrySet);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableSortedMap.of("one", 1, "three", 3, "two", 4),
            mapEntry("one", 1),