*/
    Set<List<E>> getAllStates();
  }

  /**
   * Returns a {@link ConcurrentlyMutatedList} that performs the given operations as its concurrent
   * modifications. The mutations occur in the same thread as the triggering method call.
   */
  private static ConcurrentlyMutatedList<Integer> newConcurrentlyMutatedList(
      final Collection<Integer> initialContents,

     */
    Set<List<E>> getAllStates();
  }

  /**
   * Returns a {@link ConcurrentlyMutatedList} that performs the given operations as its concurrent
   * modifications. The mutations occur in the same thread as the triggering method call.
   */
  private static ConcurrentlyMutatedList<Integer> newConcurrentlyMutatedList(
      final Collection<Integer> initialContents,