Question: when was the constitution of the united states of america written
[{'answer': '1787', 'provenance': [{'wikipedia_id': '31644', 'title': 'Constitution of the United States', 'start_paragraph_id': 13, 'start_character': 677, 'end_paragraph_id': 13, 'end_character': 681, 'bleu_score': 1.0, 'section': 'Section::::Background.:Articles of Confederation.\n'}]}]