Question: when was the bishop of rome first called pope
[{'answer': 'the mid-10th century', 'provenance': [{'wikipedia_id': '23056', 'title': 'Pope', 'start_paragraph_id': 7, 'start_character': 516, 'end_paragraph_id': 7, 'end_character': 536, 'bleu_score': 1.0, 'section': 'Section::::History.:Title and etymology.\n'}]}, {'provenance': [{'wikipedia_id': '23056', 'title': 'Pope', 'start_paragraph_id': 7, 'start_character': 4, 'end_paragraph_id': 7, 'end_character': 686, 'bleu_score': 0.931194876787181, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6316929262963363657}, 'section': 'Section::::History.:Title and etymology.\n'}]}]