code: public static List<Monomer> getListOfHandledMonomers(List<MonomerNotation> monomerNotations)
        throws HELM2HandledException, ChemistryException{
      List<Monomer> items = new ArrayList<Monomer>();
      for (int i = 0; i < monomerNotations.size(); i++) {
        MonomerNotation monomerNotation = monomerNotations.get(i);
  
        /* group element */
        if (monomerNotation instanceof MonomerNotationGroup ) {
      	  items.add(new Monomer(monomerNotation.getType(), monomerNotation.getType().equals("RNA") ? "Branch"
        	  		+ "" : "Backbone","X", "X"));
        }else if( monomerNotation instanceof MonomerNotationList){
      	  throw new HELM2HandledException("Functions can't be called for HELM2 objects");
        } else {
          try {
            int count = Integer.parseInt(monomerNotation.getCount());
            // #189 github Issue, see https://github.com/PistoiaHELM/HELMWebEditor/issues/189
            if (count == 0 ) {
              throw new HELM2HandledException("Functions can't be called for HELM2 objects");
            }
  
             for (int j = 0; j < count; j++) {
            items.addAll(Validation.getAllMonomers(monomerNotation, i));
            }
          } catch (NumberFormatException | MonomerException | IOException | NotationException | CTKException e) {
            e.printStackTrace();
            throw new HELM2HandledException("Functions can't be called for HELM2 objects");
          }
  
        }
      }
      return items;
    }
docs: method to get all HELM1 valid MonomerNotations Only on these monomers
  required HELM1 functions are performed
  
  @param monomerNotations List of MonomerNotation
  @return List of Monomer
  @throws HELM2HandledException if the HELM2 features were there
  @throws ChemistryException if the Chemistry Engine can not be initialized