* @throws IllegalArgumentException if duplicate key pairs were added
     */
    public ImmutableTable<R, C, V> build() {
      return buildOrThrow();
    }

    /**
     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
     * added.
     *
     * @throws IllegalArgumentException if duplicate key pairs were added
     * @since 31.0
     */

    }

    /**
     * Adds {@code element} to the {@code ImmutableSortedSet}. If the {@code ImmutableSortedSet}
     * already contains {@code element}, then {@code add} has no effect. (only the previously added
     * element is retained).
     *
     * @param element the element to add
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code element} is null
     */

    // of course, this test doesn't prove that anything actually happened in parallel...
  }

  // TODO(kevinb): switch to importing Truth's assertThat(DoubleStream) if we get that added
  private static IterableSubject assertThatDoubleStream(DoubleStream stream) {
    return assertThat(Doubles.asList(stream.toArray()));
  }

    List<String> alreadyThere = newArrayList("already", "there");
    List<String> freshlyAdded = newArrayList("freshly", "added");

    boolean changed = Iterables.addAll(alreadyThere, freshlyAdded);
    assertThat(alreadyThere).containsExactly("already", "there", "freshly", "added").inOrder();
    assertTrue(changed);
  }

  private static void assertCanIterateAgain(Iterable<?> iterable) {

    }

    /**
     * The number of permutations with repeated elements is calculated as follows:
     *
     * <ul>
     *   <li>For an empty list, it is 1 (base case).
     *   <li>When r numbers are added to a list of n-r elements, the number of permutations is
     *       increased by a factor of (n choose r).
     * </ul>
     */
    private static <E> int calculateSize(

   * other utilities in this package.
   *
   * <p><b>Note:</b> this method simply delegates to the JDK method {@link Float#compare}. It is
   * provided for consistency with the other primitive types, whose compare methods were not added
   * to the JDK until JDK 7.
   *
   * @param a the first {@code float} to compare
   * @param b the second {@code float} to compare
   * @return the result of invoking {@link Float#compare(float, float)}
   */

  }

  // ConcurrentMap methods

  @Override
  public boolean isEmpty() {
    /*
     * Sum per-segment modCounts to avoid mis-reporting when elements are concurrently added and
     * removed in one segment while checking another, in which case the table was never actually
     * empty at any point. (The sum ensures accuracy up through at least 1<<31 per-segment

    return new HashSet<>();
  }

  /**
   * Creates a <i>mutable</i> {@code HashSet} instance initially containing the given elements.
   *
   * <p><b>Note:</b> if elements are non-null and won't be added or removed after this point, use
   * {@link ImmutableSet#of()} or {@link ImmutableSet#copyOf(Object[])} instead. If {@code E} is an
   * {@link Enum} type, use {@link EnumSet#of(Enum, Enum[])} instead. Otherwise, strongly consider

    int added = 0;
    boolean interrupted = false;
    try {
      while (added < numElements) {
        // we could rely solely on #poll, but #drainTo might be more efficient when there are
        // multiple elements already available (e.g. LinkedBlockingQueue#drainTo locks only once)
        added += q.drainTo(buffer, numElements - added);

  }

  public void testExceptionThrown_whileClosingLastCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

    IOException exception = new IOException();

    // c1 is added first, closed last
    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(exception));
    TestCloseable c2 = closer.register(TestCloseable.normal());

    try {
      closer.close();