Question: what is the length of term of office for a supreme court justice
[{'answer': 'lifetime tenure', 'provenance': [{'wikipedia_id': '31737', 'title': 'Supreme Court of the United States', 'start_paragraph_id': 2, 'start_character': 145, 'end_paragraph_id': 2, 'end_character': 160, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]