code: public static <T> Reducer<PersistentSortedSet<T>,T> toPersistentSortedSet() {
          return Reducer.fromMonoid(Monoids.concatPersistentCollection(TreeSet.empty(Comparators.naturalOrderIdentityComparator())),
                  a -> TreeSet.of(Comparators.naturalOrderIdentityComparator(),a));
  
      }
docs: <pre>
  {@code
  PersistentSortedSet<Integer> q = Reducers.toPersistentSortedSet()
  .foldMap(Stream.of(1,2,3,4));
  
  }
  </pre>
  @return Reducer to POrderedSet