Question: what did the bill of rights added to the constitution
[{'answer': 'December 15 , 1791', 'provenance': [{'wikipedia_id': '9119240', 'title': 'United States Bill of Rights', 'start_paragraph_id': 2, 'start_character': 628, 'end_paragraph_id': 2, 'end_character': 646, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]