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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_tx_identity_info(self, tx_ac):
 """returns features associated with a single transcript. :param tx_ac: transcript accession with version (e.g., 'NM_199425.2') :type tx_ac: str # database output tx_ac | NM_199425.2 alt_ac | NM_199425.2 alt_aln_method | transcript cds_start_i | 283 cds_end_i | 1003 lengths | {707,79,410} hgnc | VSX1 """

        rows = self._fetchall(self._queries['tx_identity_info'], [tx_ac])
        if len(rows) == 0:
            raise HGVSDataNotAvailableError(
                "No transcript definition for (tx_ac={tx_ac})".format(tx_ac=tx_ac))
        return rows[0]