Who was pope the longest?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q19546', 'id': 0, 'label': 'pope'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q43720', 'id': 1, 'label': 'Pius IX'}, {'type': 'INTERNAL', 'name_': 'Q954152', 'id': 2, 'label': '1846 papal conclave'}], 'links': [{'name_': 'P541', 'source': 2, 'target': 0, 'label': 'office contested'}, {'name_': 'P991', 'source': 2, 'target': 1, 'label': 'successful candidate'}]}