code: public CDSSequence addCDS(AccessionID accession, int begin, int end, int phase) throws Exception {
  		if (cdsSequenceHashMap.containsKey(accession.getID())) {
  			throw new Exception("Duplicate accesion id " + accession.getID());
  		}
  		CDSSequence cdsSequence = new CDSSequence(this, begin, end, phase); //sense should be the same as parent
  		cdsSequence.setAccession(accession);
  		cdsSequenceList.add(cdsSequence);
  		Collections.sort(cdsSequenceList, new CDSComparator());
  		cdsSequenceHashMap.put(accession.getID(), cdsSequence);
  		return cdsSequence;
  	}
docs: Add a Coding Sequence region with phase to the transcript sequence
  @param accession
  @param begin
  @param end
  @param phase 0,1,2
  @return