public abstract Builder<E> add(E element);

    @CanIgnoreReturnValue
    public Builder<E> add(E... elements) {
      checkNotNull(elements); // for GWT
      for (E element : elements) {
        add(checkNotNull(element));
      }
      return this;
    }

    @CanIgnoreReturnValue
    public Builder<E> addAll(Iterable<? extends E> elements) {
      checkNotNull(elements); // for GWT

      }
    }
  }

  /**
   * Invokes {@code queue.}{@link BlockingQueue#put(Object) put(element)} uninterruptibly.
   *
   * @throws ClassCastException if the class of the specified element prevents it from being added
   *     to the given queue
   * @throws IllegalArgumentException if some property of the specified element prevents it from
   *     being added to the given queue
   */
  @J2ktIncompatible

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

  @CollectionFeature.Require(KNOWN_ORDER)
  @CollectionSize.Require(SEVERAL)
  public void testPeek_sizeMany() {
    assertEquals("sizeManyQueue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

      }
    }

    return !iteratorA.hasNext() && !iteratorB.hasNext();
  }

  @Override
  protected int doHash(Iterable<T> iterable) {
    int hash = 78721;
    for (T element : iterable) {
      hash = hash * 24943 + elementEquivalence.hash(element);
    }
    return hash;
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object instanceof PairwiseEquivalence) {

            writer.accept("Thread: " + entry.getKey());
            final StackTraceElement[] trace = entry.getValue();
            for (final StackTraceElement element : trace) {
                writer.accept("\tat " + element);
            }
        }
    }

      return standardAddAll(collection);
    }

    @Override
    public boolean add(T element) {
      return standardAdd(element);
    }

    @Override
    public void clear() {
      standardClear();
    }

    @Override
    public int count(Object element) {
      return standardCount(element);
    }

    @Override
    public boolean contains(Object object) {

                  protected Set<String> create(String[] elements) {
                    checkArgument(elements.length == 3);
                    // Put the sets in different orders for the hell of it
                    return Sets.union(
                        Sets.newLinkedHashSet(asList(elements)),
                        Sets.newLinkedHashSet(asList(elements[1], elements[0], elements[2])));
                  }
                })

    addEdge(N1, N1, E11);
    assertThat(network.outDegree(N1)).isEqualTo(1);
    addEdge(N1, N2, E12);
    assertThat(network.outDegree(N1)).isEqualTo(2);
  }

  // Element Mutation

  @Test
  public void addEdge_existingNodes() {
    assume().that(graphIsMutable()).isTrue();

    // Adding nodes initially for safety (insulating from possible future

            new TestEnumSetGenerator() {
              @Override
              public Set<AnEnum> create(AnEnum[] elements) {
                return (elements.length == 0)
                    ? EnumSet.noneOf(AnEnum.class)
                    : EnumSet.copyOf(MinimalCollection.of(elements));
              }
            })
        .named("EnumSet")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,

                    List<Integer> columnKeys = Lists.newArrayList();
                    for (Object element : elements) {
                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      columnKeys.add(cell.getColumnKey());