code: def _prepare_drb_allele_name(self, parsed_beta_allele):
          
          if "DRB" not in parsed_beta_allele.gene:
              raise ValueError("Unexpected allele %s" % parsed_beta_allele)
          return "%s_%s%s" % (
              parsed_beta_allele.gene,
              parsed_beta_allele.allele_family,
              parsed_beta_allele.allele_code)
docs: Assume that we're dealing with a human DRB allele
          which NetMHCIIpan treats differently because there is
          little population diversity in the DR-alpha gene