Question: when did the library of alexandria burn down
[{'answer': '48 BC', 'provenance': [{'wikipedia_id': '17726', 'title': 'Library of Alexandria', 'start_paragraph_id': 3, 'start_character': 673, 'end_paragraph_id': 3, 'end_character': 678, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]