creates GFE from HLA sequence and locus

        :param locus: string containing HLA locus.
        :param sequence: string containing sequence data.

        :return: GFEobject.

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