code: def search_references(
              self, reference_set_id, accession=None, md5checksum=None):
          
          request = protocol.SearchReferencesRequest()
          request.reference_set_id = reference_set_id
          request.accession = pb.string(accession)
          request.md5checksum = pb.string(md5checksum)
          request.page_size = pb.int(self._page_size)
          return self._run_search_request(
              request, "references", protocol.SearchReferencesResponse)
docs: Returns an iterator over the References fulfilling the specified
          conditions from the specified Dataset.
  
          :param str reference_set_id: The ReferenceSet to search.
          :param str accession: If not None, return the references for which the
              `accession` matches this string (case-sensitive, exact match).
          :param str md5checksum: If not None, return the references for which
              the `md5checksum` matches this string (case-sensitive, exact
              match).
          :return: An iterator over the :class:`ga4gh.protocol.Reference`
              objects defined by the query parameters.