Who was famed author Mary Shelley's husband?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q47152', 'id': 0, 'label': 'Mary Shelley'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q101638', 'id': 1, 'label': 'Mary Wollstonecraft'}, {'type': 'INTERNAL', 'name_': 'Q21278016', 'id': 2, 'label': None}], 'links': [{'name_': 'P921', 'source': 2, 'target': 0, 'label': 'main subject'}, {'name_': 'P921', 'source': 2, 'target': 1, 'label': 'main subject'}]}