Question: who was the last us president to be assassinated
[{'answer': 'John F. Kennedy', 'provenance': [{'wikipedia_id': '574536', 'title': 'List of United States presidential assassination attempts and plots', 'start_paragraph_id': 1, 'start_character': 416, 'end_paragraph_id': 1, 'end_character': 431, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]