Question: who is the mayor of san francisco california
[{'answer': 'Ed Lee', 'provenance': [{'wikipedia_id': '3381306', 'title': 'Mayor of San Francisco', 'start_paragraph_id': 3, 'start_character': 162, 'end_paragraph_id': 3, 'end_character': 168, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]