* this method returns {@code true} if {@code iterable1} and {@code iterable2} contain the same
   * number of elements and every element of {@code iterable1} is equal to the corresponding element
   * of {@code iterable2}.
   */
  public static boolean elementsEqual(Iterable<?> iterable1, Iterable<?> iterable2) {
    if (iterable1 instanceof Collection && iterable2 instanceof Collection) {

  public static <T extends @Nullable Object> Iterable<T> concat(
      Iterable<? extends T> a,
      Iterable<? extends T> b,
      Iterable<? extends T> c,
      Iterable<? extends T> d) {
    return FluentIterable.concat(a, b, c, d);
  }

  /**
   * Combines multiple iterables into a single iterable. The returned iterable has an iterator that

    /**
     * Returns an {@link Iterable} that wraps a {@link ClassIterator} for use in a for-each statement.
     *
     * @param clazz the class (must not be {@literal null})
     * @return an {@link Iterable} wrapping a {@link ClassIterator}
     */
    public static Iterable<Class<?>> iterable(final Class<?> clazz) {
        return iterable(clazz, true);
    }

    /**

    }

    /**
     * Returns an {@link Iterable} that wraps a {@link LineIterator} for use in enhanced for-loops.
     *
     * @param reader
     *            The {@link BufferedReader} to read strings from. Must not be {@literal null}.
     * @return An {@link Iterable} that wraps a {@link LineIterator}.
     */
    public static Iterable<String> iterable(final BufferedReader reader) {

    private final boolean errors;

    private final T value;

    private final Iterable<? extends ModelProblem> problems;

    private Result(boolean errors, T model, Iterable<? extends ModelProblem> problems) {
        this.errors = errors;
        this.value = model;
        this.problems = problems;
    }

    public Iterable<? extends ModelProblem> getProblems() {
        return problems;
    }

    Iterable<String> iterable = singletonList("foo");
    assertEquals("foo", Iterables.getLast(iterable, "bar"));
  }

  public void testGetLast_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", Iterables.getLast(iterable, "bar"));
  }

  public void testGetLast_withDefault_empty_null() {
    Iterable<String> iterable = emptyList();

    protected int index = 0;

    /**
     * Returns an {@link Iterable} that wraps the array for use in a for-each statement.
     *
     * @param <T> the type of elements
     * @param items the array of elements to iterate (must not be {@literal null})
     * @return an {@link Iterable} wrapping the array
     */
    public static <T> Iterable<T> iterable(final T... items) {
        assertArgumentNotNull("items", items);

    /**
     * Returns an {@link Iterable} that wraps a {@link SingleValueIterator} for use in a for-each statement.
     *
     * @param <E> the element type
     * @param value the single value returned by the iterator
     * @return an {@link Iterable} wrapping a {@link SingleValueIterator}
     */
    public static <E> Iterable<E> iterable(final E value) {
        return () -> new SingleValueIterator<>(value);

    PUT_BOOLEAN() {
      @Override
      void performAction(Random random, Iterable<? extends PrimitiveSink> sinks) {
        boolean value = random.nextBoolean();
        for (PrimitiveSink sink : sinks) {
          sink.putBoolean(value);
        }
      }
    },
    PUT_BYTE() {
      @Override
      void performAction(Random random, Iterable<? extends PrimitiveSink> sinks) {
        int value = random.nextInt();

    multimap().putAll(k0(), Collections.emptyList());
    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAllOnlyCallsIteratorOnce() {
    Iterable<V> iterable =
        new Iterable<V>() {
          private boolean calledIteratorAlready = false;

          @Override
          public Iterator<V> iterator() {
            checkState(!calledIteratorAlready);