Question: who is the guy playing the piano in mamma mia
[{'answer': 'Benny Andersson', 'provenance': [{'wikipedia_id': '8425661', 'title': 'Mamma Mia! (film)', 'start_paragraph_id': 1, 'start_character': 348, 'end_paragraph_id': 1, 'end_character': 363, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '8425661', 'title': 'Mamma Mia! (film)', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 59, 'bleu_score': 0.725979529115477, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14179974877774151563}, 'section': 'Section::::Cast.\n'}]}]