Writes a intermediate temporary sorted file

        :param lines: The lines to write.
        :param fname: The name of the temporary file.
        :return:

def _write(self, lines, fname):
        """
        Writes a intermediate temporary sorted file

        :param lines: The lines to write.
        :param fname: The name of the temporary file.
        :return:
        """
        with open(fname, 'wb') as out_fhndl:
            for line in sorted(lines, key=self.key):
                pickle.dump(line, out_fhndl)