Question: what type of song did schubert specialize in
[{'answer': 'Lieder', 'provenance': [{'wikipedia_id': '44888', 'title': 'Franz Schubert', 'start_paragraph_id': 1, 'start_character': 245, 'end_paragraph_id': 1, 'end_character': 251, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]