code: private IChemModel readChemModel(IChemModel chemModel) throws CDKException {
          IReactionSet setOfReactions = chemModel.getReactionSet();
          if (setOfReactions == null) {
              setOfReactions = chemModel.getBuilder().newInstance(IReactionSet.class);
          }
          chemModel.setReactionSet(readReactionSet(setOfReactions));
          return chemModel;
      }
docs: Read a IChemModel from a file in MDL RDF format.
  
  @param  chemModel The IChemModel
  @return           The IChemModel that was read from the RDF file