def METHOD_NAME(sentences, mentions):
    mentions_per_sent = {}
    for m in mentions:
        sent_idx = int(m["sent_idx"])
        curr_ments = mentions_per_sent.get(sent_idx, [])
        curr_ments.append(m)
        mentions_per_sent[sent_idx] = curr_ments
    pairs = []
    for idx, sent in enumerate(sentences):
        pairs.append((sent, mentions_per_sent.get(idx, [])))
    return pairs