def _multi_bleu(hypothesis, reference_set, aligner):
    """
    Compute a list of scores with the aligner.

    :param hypothesis: a single hypothesis.
    :param reference_set: a reference set.
    :param aligner: a callable to compute the semantic similarity of a hypothesis
    and a list of references.
    :return: List[float]
    """
    return [aligner(hypothesis, refs) for refs in reference_set]