// addListener says that listeners execute 'immediate' if the future isDone(). However, our
    // protocol for completing a future is to assign the value field (which sets isDone to true) and
    // then to release waiters, followed by executing afterDone(), followed by releasing listeners.
    // That means that it is possible to observe that the future isDone and that your listeners

      // substitute an empty ImmutableSet to the user in place of this
      if (object instanceof CartesianSet) {
        CartesianSet<?> that = (CartesianSet<?>) object;
        return this.axes.equals(that.axes);
      }
      if (object instanceof Set) {
        Set<?> that = (Set<?>) object;
        return this.size() == that.size() && this.containsAll(that);
      }

    }
  }

  /**
   * Returns a builder that creates immutable sorted maps whose keys are ordered by their natural
   * ordering. The sorted maps use {@link Ordering#natural()} as the comparator.
   */
  public static <K extends Comparable<?>, V> Builder<K, V> naturalOrder() {
    return new Builder<>(Ordering.natural());
  }

  /**
   * Returns a builder that creates immutable sorted maps with an explicit comparator. If the

   * Creates an index {@code ImmutableListMultimap} that contains the results of applying a
   * specified function to each item in an {@code Iterable} of values. Each value will be stored as
   * a value in the resulting multimap, yielding a multimap with the same size as the input
   * iterable. The key used to store that value in the multimap will be the result of calling the

/**
 * This class contains static utility methods that operate on or return objects of type {@link
 * Iterator}. Except as noted, each method has a corresponding {@link Iterable}-based method in the
 * {@link Iterables} class.
 *
 * <p><i>Performance notes:</i> Unless otherwise noted, all of the iterators produced in this class
 * are <i>lazy</i>, which means that they only advance the backing iteration when absolutely
 * necessary.
 *