code: @Override
      public Iterable<IMapping> mappings() {
          return new Iterable<IMapping>() {
  
              @Override
              public Iterator<IMapping> iterator() {
                  return new MappingIterator();
              }
          };
      }
docs: Returns the mappings between the reactant and the product side.
  
  @return An Iterator to the Mappings.
  @see    #addMapping