Question: why are presidents sworn in on the bible
[{'answer': 'convention', 'provenance': [{'wikipedia_id': '694601', 'title': 'Oath of office of the President of the United States', 'start_paragraph_id': 14, 'start_character': 3, 'end_paragraph_id': 14, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Use of Bibles.\n'}]}, {'provenance': [{'wikipedia_id': '694601', 'title': 'Oath of office of the President of the United States', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 490, 'bleu_score': 0.9768747032089851, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14758806296258300137}, 'section': 'Section::::Use of Bibles.\n'}]}]