Question: what is one flat in the key signature
[{'answer': 'B ♭', 'provenance': [{'wikipedia_id': '17394', 'title': 'Key signature', 'start_paragraph_id': 9, 'start_character': 411, 'end_paragraph_id': 9, 'end_character': 412, 'bleu_score': 1.0, 'section': 'Section::::Conventions.\n'}]}]