code: @Override
      public Iterable<IChemObject> relatedChemObjects() {
          return new Iterable<IChemObject>() {
  
              @Override
              public Iterator<IChemObject> iterator() {
                  return new ChemObjectIterator();
              }
          };
      }
docs: Returns an Iterable to the two IChemObjects.
  Iterable.remove() is not implemented.
  
  @return An Iterable to two IChemObjects that define the mapping