code: public static <K,V> RelationFactory<K,V> mapSet(MapFactory<K,Set<V>> mapFact,
  						    SetFactory<V> setFact) {
  	return new jpaul.DataStructs.MapSetRelationFactory<K,V>(mapFact, setFact);	
      }
docs: Returns a relation factory that generates
  <code>Relation</code>s interface backed by a <code>Map</code>
  from keys to <code>Set</code>s of values.  The map is created
  by <code>mapFact</code> and the sets by <code>setFact</code>.
  
  The two parameters allow the programmer to finely tune the
  relations from the program.