In how many games has Princess Peach been the only playable character?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'INTERNAL', 'name_': 'Q522508', 'id': 0, 'label': 'Super Paper Mario'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q20203549', 'id': 1, 'label': 'Super Mario universe'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q507001', 'id': 2, 'label': 'Princess Peach'}], 'links': [{'name_': 'P840', 'source': 0, 'target': 1, 'label': 'narrative location'}, {'name_': 'P674', 'source': 0, 'target': 2, 'label': 'characters'}]}