Question: who was the president when south carolina seceded
[{'answer': 'James Buchanan', 'provenance': [{'wikipedia_id': '6696464', 'title': 'South Carolina in the American Civil War', 'start_paragraph_id': 15, 'start_character': 553, 'end_paragraph_id': 15, 'end_character': 567, 'bleu_score': 1.0, 'section': 'Section::::Secession.\n'}]}, {'provenance': [{'wikipedia_id': '6696464', 'title': 'South Carolina in the American Civil War', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 655, 'bleu_score': 0.9815648442794911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4495541469634105355}, 'section': 'Section::::Secession.\n'}]}]