Question: what's it called when a song changes key
[{'answer': 'modulation', 'provenance': [{'wikipedia_id': '237665', 'title': 'Modulation (music)', 'start_paragraph_id': 1, 'start_character': 10, 'end_paragraph_id': 1, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '237665', 'title': 'Modulation (music)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 334, 'bleu_score': 0.7923416299407441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6296745848766359398}, 'section': 'Section::::Abstract.'}]}]