How to use the sacrebleu.sentence_chrf function in sacrebleu

def __init__(self, metric: str,
                 return_score: bool = False) -> None:
        if metric == C.RERANK_BLEU:
            self.scoring_function = sacrebleu.sentence_bleu
        elif metric == C.RERANK_CHRF:
            self.scoring_function = sacrebleu.sentence_chrf
        else:
            raise utils.SockeyeError("Scoring metric '%s' unknown. Choices are: %s" % (metric, C.RERANK_METRICS))

        self.return_score = return_score

def score_sentence(self, hyp, ref, lang=None):
        return sacrebleu.sentence_chrf(hyp, ref)

def _get_sent_chrf(
        hypothesis: List[str], references: List[List[str]],
        extra_args: Optional[Dict[str, str]] = None
):
    return [
        sb.sentence_chrf(h, r).score for h, r in zip(hypothesis, references[0])
    ]