Question: who killed cheyenne in once upon a time in the west
[{'answer': 'Morton', 'provenance': [{'wikipedia_id': '284676', 'title': 'Once Upon a Time in the West', 'start_paragraph_id': 6, 'start_character': 547, 'end_paragraph_id': 6, 'end_character': 553, 'bleu_score': 1.0, 'section': 'Section::::Plot.\n'}]}]