Question: who is currently the longest serving member of the senate
[{'answer': 'Patrick Leahy', 'provenance': [{'wikipedia_id': '10644188', 'title': 'List of members of the United States Congress by longevity of service', 'start_paragraph_id': 8, 'start_character': 210, 'end_paragraph_id': 8, 'end_character': 223, 'bleu_score': 1.0, 'section': 'Section::::Senate time.\n'}]}]