Question: who played king arthur in monty pythons holy grail
[{'answer': 'Graham Chapman', 'provenance': [{'wikipedia_id': '19701', 'title': 'Monty Python and the Holy Grail', 'start_paragraph_id': 1, 'start_character': 153, 'end_paragraph_id': 1, 'end_character': 167, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]