def get_entity_mention_by_sent_id(graph, sent_id):
    """
    Returns all entity mentions in a given sentence.
    :param graph: the OKR graph
    :param sent_id: the sentence ID
    :return all entity mentions in a given sentence
    """
    return { ent_id : mention for ent_id, ent in graph.entities.iteritems()
             for mention_id, mention in ent.mentions.iteritems()
             if mention.sentence_id == sent_id }