return ((Multiset<?>) elements).elementSet().size();
    }
    return 11; // initial capacity will be rounded up to 16
  }

  /**
   * Returns an unmodifiable view of the union of two multisets. In the returned multiset, the count
   * of each element is the <i>maximum</i> of its counts in the two backing multisets. The iteration

    return result;
  }

  /**
   * Returns a new range set consisting of the union of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).addAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> union(RangeSet<C> other) {
    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
  }

    return result;
  }

  /**
   * Returns a new range set consisting of the union of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).addAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> union(RangeSet<C> other) {
    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
  }

                            ? Sets.newHashSet(Arrays.asList(elements).subList(1, size))
                            : Sets.<String>newHashSet();
                    return Sets.union(set1, set2);
                  }
                })
            .named("Sets.union")
            .withFeatures(CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(

            .add(Range.closedOpen(5, 10))
            .add(Range.closedOpen(12, 15))
            .add(Range.openClosed(15, 17))
            .add(Range.open(19, 20))
            .build();

    assertThat(RANGE_SET_ONE.union(RANGE_SET_TWO)).isEqualTo(expected);
  }

  public void testIntersection() {
    RangeSet<Integer> expected =
        ImmutableRangeSet.<Integer>builder()
            .add(Range.closed(2, 3))

            .add(Range.closedOpen(5, 10))
            .add(Range.closedOpen(12, 15))
            .add(Range.openClosed(15, 17))
            .add(Range.open(19, 20))
            .build();

    assertThat(RANGE_SET_ONE.union(RANGE_SET_TWO)).isEqualTo(expected);
  }

  public void testIntersection() {
    RangeSet<Integer> expected =
        ImmutableRangeSet.<Integer>builder()
            .add(Range.closed(2, 3))

     * @since 20.0 (present with return type {@link Iterator} since 2.0)
     */
    @Override
    public abstract UnmodifiableIterator<E> iterator();
  }

  /**
   * Returns an unmodifiable <b>view</b> of the union of two sets. The returned set contains all
   * elements that are contained in either backing set. Iterating over the returned set iterates

                            ? Sets.newHashSet(Arrays.asList(elements).subList(1, size))
                            : Sets.<String>newHashSet();
                    return Sets.union(set1, set2);
                  }
                })
            .named("Sets.union")
            .withFeatures(CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(

  }

  @Override
  public Set<E> adjacentEdges(E edge) {
    EndpointPair<N> endpointPair = incidentNodes(edge); // Verifies that edge is in this network.
    Set<E> endpointPairIncidentEdges =
        Sets.union(incidentEdges(endpointPair.nodeU()), incidentEdges(endpointPair.nodeV()));
    return edgeInvalidatableSet(
        Sets.difference(endpointPairIncidentEdges, ImmutableSet.of(edge)), edge);
  }

  @Override

   *   <li>{@code [2, 4)} and {@code [4, 6)} are connected, because both enclose the empty range
   *       {@code [4, 4)}
   * </ul>
   *
   * <p>Note that this range and {@code other} have a well-defined {@linkplain #span union} and
   * {@linkplain #intersection intersection} (as a single, possibly-empty range) if and only if this
   * method returns {@code true}.
   *