Executes sacrebleu and returns BLEU score.

        :param detok_eval_path: path to the test file
        :param reference_path: path to the reference file

def run_sacrebleu(self, detok_eval_path, reference_path):
        """
        Executes sacrebleu and returns BLEU score.

        :param detok_eval_path: path to the test file
        :param reference_path: path to the reference file
        """
        if reference_path is None:
            reference_path = os.path.join(self.dataset_dir,
                                          config.TGT_TEST_TARGET_FNAME)
        sacrebleu_params = '--score-only -lc --tokenize intl'
        logging.info(f'Running sacrebleu (parameters: {sacrebleu_params})')
        sacrebleu = subprocess.run([f'sacrebleu --input {detok_eval_path} \
                                    {reference_path} {sacrebleu_params}'],
                                   stdout=subprocess.PIPE, shell=True)
        test_bleu = float(sacrebleu.stdout.strip())
        return test_bleu