@CanIgnoreReturnValue
  @Override
  Hasher putLong(long l);

  /** Equivalent to {@code putInt(Float.floatToRawIntBits(f))}. */
  @CanIgnoreReturnValue
  @Override
  Hasher putFloat(float f);

  /** Equivalent to {@code putLong(Double.doubleToRawLongBits(d))}. */
  @CanIgnoreReturnValue
  @Override
  Hasher putDouble(double d);

  /** Equivalent to {@code putByte(b ? (byte) 1 : (byte) 0)}. */
  @CanIgnoreReturnValue

  /**
   * Determines if the given iterable contains no elements.
   *
   * <p>There is no precise {@link Iterator} equivalent to this method, since one can only ask an
   * iterator whether it has any elements <i>remaining</i> (which one does using {@link
   * Iterator#hasNext}).
   *
   * <p><b>{@code Stream} equivalent:</b> {@code !stream.findAny().isPresent()}
   *
   * @return {@code true} if the iterable contains no elements

   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
   * {@code Optional.ofNullable}.
   */
  public static <T> Optional<T> fromNullable(@Nullable T nullableReference) {
    return (nullableReference == null) ? Optional.<T>absent() : new Present<T>(nullableReference);
  }

  /**
   * Returns the equivalent {@code com.google.common.base.Optional} value to the given {@code

   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
   * {@code Optional.ofNullable}.
   */
  public static <T> Optional<T> fromNullable(@Nullable T nullableReference) {
    return (nullableReference == null) ? Optional.<T>absent() : new Present<T>(nullableReference);
  }

  /**
   * Returns the equivalent {@code com.google.common.base.Optional} value to the given {@code

   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#count}.
   */
  public final int size() {
    return Iterables.size(getDelegate());
  }

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */

   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#count}.
   */
  public final int size() {
    return Iterables.size(getDelegate());
  }

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */

   * stream is empty.
   *
   * <p>Equivalent to {@code stream.reduce((a, b) -> b)}, but may perform significantly better. This
   * method's runtime will be between O(log n) and O(n), performing better on <a
   * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
   * streams.
   *
   * <p>If the stream has nondeterministic order, this has equivalent semantics to {@link

  private CollectorTester(
      Collector<T, A, R> collector, BiPredicate<? super R, ? super R> equivalence) {
    this.collector = checkNotNull(collector);
    this.equivalence = checkNotNull(equivalence);
  }

  /**
   * Different orderings for combining the elements of an input array, which must all produce the
   * same result.
   */
  enum CollectStrategy {

 * the same single element. The total number of occurrences of an element in a multiset is called
 * the <i>count</i> of that element (the terms "frequency" and "multiplicity" are equivalent, but
 * not used in this API). Since the count of an element is represented as an {@code int}, a multiset
 * may never contain more than {@link Integer#MAX_VALUE} occurrences of any one element.
 *

        toImmutableEnumMap(Entry::getKey, Entry::getValue);
    Equivalence<ImmutableMap<AnEnum, Integer>> equivalence =
        Equivalence.equals().<Entry<AnEnum, Integer>>pairwise().onResultOf(ImmutableMap::entrySet);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableMap.of(AnEnum.A, 1, AnEnum.C, 2, AnEnum.E, 3),