/** Constructor for use by subclasses. */
  protected AbstractIterator() {}

  private enum State {
    /** We have computed the next element and haven't returned it yet. */
    READY,

    /** We haven't yet computed or have already returned the element. */
    NOT_READY,

    /** We have reached the end of the data and are finished. */
    DONE,

    /** We've suffered an exception and are kaput. */

      // the worker has yet to start) then we don't need to start the worker.
      if (workerRunningState == RUNNING || workerRunningState == QUEUED) {
        queue.add(task);
        return;
      }

      oldRunCount = workerRunCount;

      // If the worker is not yet running, the delegate Executor might reject our attempt to start

   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.
   *   <li>null, if no entries have yet been added to the map
   * </ul>
   */
  @CheckForNull private transient Object table;

  /**
   * Contains the logical entries, in the range of [0, size()). The high bits of each int are the

   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.
   *   <li>null, if no entries have yet been added to the map
   * </ul>
   */
  @CheckForNull private transient Object table;

  /**
   * Contains the logical entries, in the range of [0, size()). The high bits of each int are the

          annotationClass.getDeclaringClass(),
          returnType.getComponentType());
    }
  }

  // This is public so that tests for Feature enums we haven't yet imagined
  // can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    final Class<?>[] classes = featureEnumClass.getDeclaredClasses();

  `It was much pleasanter at home,' thought poor Alice, `when one
wasn't always growing larger and smaller, and being ordered about
by mice and rabbits.  I almost wish I hadn't gone down that
rabbit-hole--and yet--and yet--it's rather curious, you know,
this sort of life!  I do wonder what CAN have happened to me!
When I used to read fairy-tales, I fancied that kind of thing
never happened, and now here I am in the middle of one!  There

   *     sure you are passing the two parameters in the right order.
   * @param actual The type that the formal type variable(s) are mapped to. It can be or contain yet
   *     other type variables, in which case these type variables will be further resolved if
   *     corresponding mappings exist in the current {@code TypeResolver} instance.
   */

 * traditional {@code Map} rely on {@code put(K, V)}, the typical mechanism for writing to this map
 * is {@code addAndGet(K, long)}, which adds a {@code long} to the value currently associated with
 * {@code K}. If a key has not yet been associated with a value, its implicit value is zero.
 *
 * <p>Most methods in this class treat absent values and zero values identically, as individually

 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Louis Wasserman
 * @since 12.0
 */
@GwtIncompatible // hasn't been tested yet
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedMultiset<E> extends ImmutableMultiset<E>
    implements SortedMultiset<E> {
  // TODO(lowasser): GWT compatibility

  /**

 *       ordered pair of keys, a row key and column key.
 *   <dt>{@link Multiset}
 *   <dd>An extension of {@link java.util.Collection} that may contain duplicate values like a
 *       {@link java.util.List}, yet has order-independent equality like a {@link java.util.Set}.
 *       One typical use for a multiset is to represent a histogram.
 *   <dt>{@link ClassToInstanceMap}