*
   * <ol>
   *   <li>calls {@link ExecutorService#shutdown()}, disabling acceptance of new submitted tasks.
   *   <li>awaits executor service termination for half of the specified timeout.
   *   <li>if the timeout expires, it calls {@link ExecutorService#shutdownNow()}, cancelling
   *       pending tasks and interrupting running tasks.

   * consistentHash(h, n)} equals:
   *
   * <ul>
   *   <li>{@code n - 1}, with approximate probability {@code 1/n}
   *   <li>{@code consistentHash(h, n - 1)}, otherwise (probability {@code 1 - 1/n})
   * </ul>
   *
   * <p>This method is suitable for the common use case of dividing work among buckets that meet the
   * following conditions:
   *
   * <ul>
   *   <li>You want to assign the same fraction of inputs to each bucket.

 *
 * <p>Some uses of this class include
 *
 * <ul>
 *   <li>As a method return type, as an alternative to returning {@code null} to indicate that no
 *       value was available
 *   <li>To distinguish between "unknown" (for example, not present in a map) and "known to have no
 *       value" (present in the map, with value {@code Optional.absent()})

   * }</pre>
   *
   * <p>returns a set containing six lists:
   *
   * <ul>
   *   <li>{@code ImmutableList.of(1, "A")}
   *   <li>{@code ImmutableList.of(1, "B")}
   *   <li>{@code ImmutableList.of(1, "C")}
   *   <li>{@code ImmutableList.of(2, "A")}
   *   <li>{@code ImmutableList.of(2, "B")}
   *   <li>{@code ImmutableList.of(2, "C")}
   * </ul>
   *

   *
   * <ul>
   *   <li>{@code null} initial state, nothing has happened.
   *   <li>{@link Cancellation} terminal state, {@code cancel} was called.
   *   <li>{@link Failure} terminal state, {@code setException} was called.
   *   <li>{@link SetFuture} intermediate state, {@code setFuture} was called.
   *   <li>{@link #NULL} terminal state, {@code set(null)} was called.

  }

  /**
   * Returns a fresh instance for {@code type} if possible. The returned instance could be:
   *
   * <ul>
   *   <li>exactly of the given type, including generic type parameters, such as {@code
   *       ImmutableList<String>};
   *   <li>of the raw type;
   *   <li>null if no value can be generated.
   * </ul>
   */
  final @Nullable Object generateFresh(TypeToken<?> type) {

      this.size = calculateSize(inputList, comparator);
    }

    /**
     * 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(

  }

  /**
   * Returns a fresh instance for {@code type} if possible. The returned instance could be:
   *
   * <ul>
   *   <li>exactly of the given type, including generic type parameters, such as {@code
   *       ImmutableList<String>};
   *   <li>of the raw type;
   *   <li>null if no value can be generated.
   * </ul>
   */
  final @Nullable Object generateFresh(TypeToken<?> type) {

     * <p>
     * Supported filters:
     * <ul>
     *     <li>"h" or "h(num)" - highest version or top list of highest ones filter</li>
     *     <li>"l" or "l(num)" - lowest version or bottom list of lowest ones filter</li>
     *     <li>"s" - contextual snapshot filter</li>
     *     <li>"e(G:A:V)" - predicate filter (leaves out G:A:V from range, if hit, V can be range)</li>
     * </ul>

 * Ordering}, including:
 *
 * <ul>
 *   <li>{@link #reverse}
 *   <li>{@link #compound(Comparator)}
 *   <li>{@link #onResultOf(Function)}
 *   <li>{@link #nullsFirst} / {@link #nullsLast}
 * </ul>
 *
 * <h4>Using</h4>
 *
 * <p>Finally, use the resulting {@code Ordering} anywhere a {@link Comparator} is required, or use
 * any of its special operations, such as:
 *
 * <ul>
 *   <li>{@link #immutableSortedCopy}