Question: when was the constitution of united states written
[{'answer': 'September 17 , 1787', 'provenance': [{'wikipedia_id': '31644', 'title': 'Constitution of the United States', 'start_paragraph_id': 78, 'start_character': 58, 'end_paragraph_id': 78, 'end_character': 77, 'bleu_score': 1.0, 'section': 'Section::::Original frame.:Closing endorsement.\n'}]}]