What is the nickname of Philadelphia?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q1345', 'id': 0, 'label': 'Philadelphia'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q84044284', 'id': 1, 'label': 'Category:Maps of Philadelphia'}], 'links': [{'name_': 'P7867', 'source': 0, 'target': 1, 'label': 'category for maps'}]}