code: public static PolymerNotation getAntiparallel(PolymerNotation polymer)
  			throws RNAUtilsException, ChemistryException, NucleotideLoadingException {
  		checkRNA(polymer);
  		PolymerNotation reversePolymer;
  		try {
  			reversePolymer = SequenceConverter.readRNA(generateAntiparallel(polymer)).getCurrentPolymer();
  			reversePolymer = new PolymerNotation(reversePolymer.getPolymerID(), reversePolymer.getPolymerElements(),
  					"Antiparallel to " + polymer.getPolymerID().getId());
  			return reversePolymer;
  		} catch (NotationException | FastaFormatException | HELM2HandledException e) {
  			e.printStackTrace();
  			throw new RNAUtilsException("The reverse polymer can not be built");
  		}
  
  	}
docs: method to get the antiparallel polymer for a rna/dna polymer
  
  @param polymer
  PolymerNotation
  @return antiparallel polymer
  @throws RNAUtilsException
  if the polymer is not rna or dna or the reverse polymer can
  not be built
  @throws ChemistryException
  if the Chemistry Engine can not be initialized
  @throws NucleotideLoadingException if nucleotides can not be loaded