How many Portal games are there?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q274897', 'id': 0, 'label': 'Portal'}, {'type': 'INTERNAL', 'name_': 'Q7231475', 'id': 1, 'label': 'Portal'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q605125', 'id': 2, 'label': 'GLaDOS'}], 'links': [{'name_': 'P527', 'source': 1, 'target': 0, 'label': 'has part(s)'}, {'name_': 'P1441', 'source': 2, 'target': 1, 'label': 'present in work'}]}