code: private static boolean hasModification(MonomerNotation monomerNotation) throws NotationException {
  
  		if (monomerNotation instanceof MonomerNotationUnitRNA) {
  			if (hasModification((MonomerNotationUnitRNA) monomerNotation)) {
  				return true;
  			}
  		} else if (monomerNotation instanceof MonomerNotationGroup) {
  			for (MonomerNotationGroupElement element : ((MonomerNotationGroup) monomerNotation).getListOfElements()) {
  				if (hasModification(element.getMonomerNotation())) {
  					return true;
  				}
  			}
  		} else if (monomerNotation instanceof MonomerNotationList) {
  			for (MonomerNotation element : ((MonomerNotationList) monomerNotation).getListofMonomerUnits()) {
  				if (hasModification(element)) {
  					return true;
  				}
  			}
  		} else {
  			throw new NotationException("Unknown MonomerNotation Type " + monomerNotation.getClass());
  		}
  		return false;
  	}
docs: method to check if the MonomerNotation contains a modification
  
  @param monomerNotation
  @return true, if the MonomerNotation contains a modification, false
  otherwise
  @throws NotationException
  if the MonomerNotation is unknown