Question: what is the bar in crossing the bar
[{'answer': 'sandbar', 'provenance': [{'wikipedia_id': '8045672', 'title': 'Crossing the Bar', 'start_paragraph_id': 1, 'start_character': 186, 'end_paragraph_id': 1, 'end_character': 193, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '8045672', 'title': 'Crossing the Bar', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 325, 'bleu_score': 0.8302828299826631, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13934519557806347149}, 'section': 'Section::::Abstract.'}]}]