Question: who sings once upon a time in the west
[{'answer': 'Ennio Morricone', 'provenance': [{'wikipedia_id': '8777710', 'title': 'Once Upon a Time in the West (soundtrack)', 'start_paragraph_id': 1, 'start_character': 57, 'end_paragraph_id': 1, 'end_character': 72, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '8777710', 'title': 'Once Upon a Time in the West (soundtrack)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 215, 'bleu_score': 0.9493253852526031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9591649424657260261}, 'section': 'Section::::Abstract.'}]}]