}

      @Override
      int maxSize() {
        return maxSize(set1);
      }
    };
  }

  /**
   * Returns an unmodifiable <b>view</b> of the symmetric difference of two sets. The returned set
   * contains all elements that are contained in either {@code set1} or {@code set2} but not in
   * both. The iteration order of the returned set is undefined.
   *