return new AbstractSet<EndpointPair<N>>() {
          @Override
          public Iterator<EndpointPair<N>> iterator() {
            return Iterators.transform(
                AbstractNetwork.this.edges().iterator(), edge -> incidentNodes(edge));
          }

          @Override
          public int size() {
            return AbstractNetwork.this.edges().size();

    }
  }

  /**
   * Verifies that an Iterator is unmodifiable.
   *
   * <p>This test only works with iterators that iterate over a finite set.
   */
  public static void assertIteratorIsUnmodifiable(Iterator<?> iterator) {
    while (iterator.hasNext()) {
      iterator.next();
      try {
        iterator.remove();
        fail("Remove on unmodifiable iterator succeeded");

      if (eventSubscribers != null) {
        // eager no-copy snapshot
        subscriberIterators.add(eventSubscribers.iterator());
      }
    }

    return Iterators.concat(subscriberIterators.iterator());
  }

  /**
   * A thread-safe cache that contains the mapping from each class to all methods in that class and

        return new AbstractSet<EndpointPair<N>>() {
          @Override
          public Iterator<EndpointPair<N>> iterator() {
            return Iterators.transform(
                AbstractNetwork.this.edges().iterator(), edge -> incidentNodes(edge));
          }

          @Override
          public int size() {
            return AbstractNetwork.this.edges().size();

  }

  public void testCopyOf_iterator_general() {
    Iterator<String> iterator = asList("a", "b", "a").iterator();
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(iterator);
    assertEquals(HashMultiset.create(asList("a", "b", "a")), multiset);
  }

  public void testCopyOf_iteratorContainingNull() {
    Iterator<String> iterator = asList("a", null, "b").iterator();

      return original.size();
    }

    @Override
    public Collection<V> values() {
      return original.values();
    }

    @Override
    Iterator<Cell<C, R, V>> cellIterator() {
      return Iterators.transform(original.cellSet().iterator(), Tables::transposeCell);
    }
  }

  private static <
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

    Iterator<Integer> iterator = ints.iterator();
    assertEquals(0, (int) numberOrdering.min(iterator));
    assertFalse(iterator.hasNext());
  }

  public void testIteratorMaxExhaustsIterator() {
    List<Integer> ints = Lists.newArrayList(9, 0, 3, 5);
    Iterator<Integer> iterator = ints.iterator();
    assertEquals(9, (int) numberOrdering.max(iterator));
    assertFalse(iterator.hasNext());

    Iterator<Integer> iterator = ints.iterator();
    assertEquals(0, (int) numberOrdering.min(iterator));
    assertFalse(iterator.hasNext());
  }

  public void testIteratorMaxExhaustsIterator() {
    List<Integer> ints = Lists.newArrayList(9, 0, 3, 5);
    Iterator<Integer> iterator = ints.iterator();
    assertEquals(9, (int) numberOrdering.max(iterator));
    assertFalse(iterator.hasNext());

    // TODO(cpovirk): are we over-wrapping?
    this.delegate = Collections.unmodifiableSet(delegate);
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return Iterators.unmodifiableIterator(delegate.iterator());
  }

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && delegate.contains(object);
  }

  @Override

      assertThat(collection.isEmpty()).isTrue();
    }
    assertThat(Iterables.size(collection)).isEqualTo(size);
    assertThat(Iterators.size(collection.iterator())).isEqualTo(size);
  }