Question: who is credited with collecting and codifying the chants of the medieval church
[{'answer': 'Pope Gregory I', 'provenance': [{'wikipedia_id': '155469', 'title': 'Gregorian chant', 'start_paragraph_id': 1, 'start_character': 309, 'end_paragraph_id': 1, 'end_character': 323, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '155469', 'title': 'Gregorian chant', 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 1022, 'bleu_score': 0.9876155018005031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18230100641761919258}, 'section': 'Section::::History.:Development of earlier plainchant.\n'}]}]