docs: def _make_gfe(self, features, locus):
          """
          creates GFE from HLA sequence and locus
  
          :param locus: string containing HLA locus.
          :param sequence: string containing sequence data.
  
          :return: GFEobject.
          """
          gfe_list = []
          for feat in sorted(self.structures[locus],
                             key=lambda k: self.structures[locus][k]):
              acc = str(0)
              if feat in features:
                  acc = str(features[feat])
              gfe_list.append(acc)
  
          gfea = '-'.join(gfe_list)
          return locus + "w" + gfea