Question: what type of music did vernon dalhart sing before switching to country music
[{'answer': 'classical music', 'provenance': [{'wikipedia_id': '1108102', 'title': 'Vernon Dalhart', 'start_paragraph_id': 6, 'start_character': 34, 'end_paragraph_id': 6, 'end_character': 49, 'bleu_score': 1.0, 'section': 'Section::::Biography.:Music career.\n'}]}, {'provenance': [{'wikipedia_id': '1108102', 'title': 'Vernon Dalhart', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 436, 'bleu_score': 0.9738505480425671, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7603746893561197454}, 'section': 'Section::::Biography.:Music career.\n'}]}]