Question: how many justices currently serve on the us supreme court
[{'answer': 'nine', 'provenance': [{'wikipedia_id': '216429', 'title': 'List of Justices of the Supreme Court of the United States', 'start_paragraph_id': 3, 'start_character': 448, 'end_paragraph_id': 3, 'end_character': 452, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '216429', 'title': 'List of Justices of the Supreme Court of the United States', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 102, 'bleu_score': 0.8852140475440831, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1183464961361237208}, 'section': 'Section::::Current justices of the Supreme Court.\n'}]}]