code: public static String generateFastaFromRNAPolymer(List<PolymerNotation> polymers)
  			throws FastaFormatException, ChemistryException {
  		StringBuilder fasta = new StringBuilder();
  		for (PolymerNotation polymer : polymers) {
  			String header = polymer.getPolymerID().getId();
  			if (polymer.getAnnotation() != null) {
  				header = polymer.getAnnotation();
  			}
  
  			fasta.append(">" + header + "\n");
  			try {
  				fasta.append(
  						generateFastaFromRNA(MethodsMonomerUtils.getListOfHandledMonomers(polymer.getListMonomers()))
  								+ "\n");
  			} catch (HELM2HandledException e) {
  				e.printStackTrace();
  				throw new FastaFormatException(e.getMessage());
  			}
  		}
  		return fasta.toString();
  	}
docs: method to generate Fasta for rna polymers
  
  @param polymers
  list of rna PolymerNotation
  @return Fasta
  @throws FastaFormatException
  if the polymers can not be transformed into FASTA
  @throws ChemistryException
  if the Chemistry Engine can not be initialized