code: private static void initMapNucleotidesNaturalAnalog() throws FastaFormatException, ChemistryException {
  		try {
  			nucleotidesNaturalAnalog = MonomerFactory.getInstance().getMonomerDB().get("RNA");
  		} catch (IOException e) {
  			e.printStackTrace();
  			LOG.error("Nucleotides can not be initialized");
  			throw new FastaFormatException(e.getMessage());
  		}
  	}
docs: method to initialize map of existing nucleotides with the natural analog
  sequence in the database
  
  @throws FastaFormatException
  if the NucleotideFactory can not be initialized
  @throws ChemistryException
  if chemistry engine can not be initialized