Question: what city was considered the center for music during the classical period
[{'answer': 'Vienna', 'provenance': [{'wikipedia_id': '5288', 'title': 'Classical period (music)', 'start_paragraph_id': 4, 'start_character': 787, 'end_paragraph_id': 4, 'end_character': 793, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '5288', 'title': 'Classical period (music)', 'start_paragraph_id': 59, 'start_character': 0, 'end_paragraph_id': 59, 'end_character': 617, 'bleu_score': 0.980097014099621, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9021477912708022527}, 'section': 'Section::::Classical influence on later composers.\n'}]}]