code: public List<RMap> bitSetToRMap(BitSet set) {
          List<RMap> rMapList = new ArrayList<RMap>();
  
          for (int x = set.nextSetBit(0); x >= 0; x = set.nextSetBit(x + 1)) {
              RNode xNode = graph.get(x);
              rMapList.add(xNode.rMap);
          }
          return rMapList;
      }
docs: Converts a RGraph bitset (set of RNode)
  to a list of RMap that represents the
  mapping between to substructures in G1 and G2
  (the projection of the RGraph bitset on G1
  and G2).
  
  @param  set  the BitSet
  @return      the RMap list