//
    // p4 inherits from p3
    // p3 inherits from p2
    // p2 inherits from p1
    // p1 inherits from p0
    // p0 inherits from super model
    //
    // or we can show it graphically as:
    //
    // p4 ---> p3 ---> p2 ---> p1 ---> p0 --> super model
    //
    // ----------------------------------------------------------------------

    @Test

@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
    implements Serializable {
  final Ordering<? super T> ordering;

  NullsFirstOrdering(Ordering<? super T> ordering) {
    this.ordering = ordering;
  }

  @Override
  public int compare(@CheckForNull T left, @CheckForNull T right) {
    if (left == right) {
      return 0;
    }

      return String.valueOf(hash);
    }
  }

  static class SlowElement extends Element {
    SlowElement(int hash) {
      super(hash);
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      return slowItDown() != 1 && super.equals(obj);
    }

    @Override
    public int hashCode() {
      return slowItDown() + hash;
    }

    @Override

                throw new IllegalStateException("Fail");
              }
              return 25;
            }
          });

  @Override
  protected void setUp() throws Exception {
    super.setUp();

    exec = Executors.newCachedThreadPool();

    task.addListener(
        new Runnable() {
          @Override
          public void run() {
            listenerLatch.countDown();
          }

    //
    // p4 inherits from p3
    // p3 inherits from p2
    // p2 inherits from p1
    // p1 inherits from p0
    // p0 inherits from super model
    //
    // or we can show it graphically as:
    //
    // p4 ---> p3 ---> p2 ---> p1 ---> p0 --> super model
    //
    // ----------------------------------------------------------------------

    @Test
    void testProjectInheritance() throws Exception {

          }
        });
  }

  static class MockReference extends FinalizableWeakReference<Object> {

    volatile boolean finalizeReferentCalled;

    MockReference(FinalizableReferenceQueue frq) {
      super(new Object(), frq);
    }

    @Override
    public void finalizeReferent() {
      finalizeReferentCalled = true;
    }
  }

  /**

                throw new IllegalStateException("Fail");
              }
              return 25;
            }
          });

  @Override
  protected void setUp() throws Exception {
    super.setUp();

    exec = Executors.newCachedThreadPool();

    task.addListener(
        new Runnable() {
          @Override
          public void run() {
            listenerLatch.countDown();
          }

  final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed

  /** Constructs a graph with the properties specified in {@code builder}. */
  StandardNetwork(NetworkBuilder<? super N, ? super E> builder) {
    this(
        builder,
        builder.nodeOrder.<N, NetworkConnections<N, E>>createMap(
            builder.expectedNodeCount.or(DEFAULT_NODE_COUNT)),

  final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed

  /** Constructs a graph with the properties specified in {@code builder}. */
  StandardNetwork(NetworkBuilder<? super N, ? super E> builder) {
    this(
        builder,
        builder.nodeOrder.<N, NetworkConnections<N, E>>createMap(
            builder.expectedNodeCount.or(DEFAULT_NODE_COUNT)),

        @Override
        @J2ktIncompatible // serialization
        @GwtIncompatible // serialization
        Object writeReplace() {
          return super.writeReplace();
        }
      };
    } else {
      return super.createAsList();
    }
  }

  @Override
  public int size() {
    long distance = domain.distance(first(), last());