Question: who composed the music for the nutcracker ballet
[{'answer': 'Pyotr Ilyich Tchaikovsky', 'provenance': [{'wikipedia_id': '284925', 'title': 'The Nutcracker', 'start_paragraph_id': 1, 'start_character': 147, 'end_paragraph_id': 1, 'end_character': 171, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]