Who was the first heavy metal band?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'INTERNAL', 'name_': 'Q6173448', 'id': 0, 'label': 'Wikipedia:Vital articles/Level/4'}, {'type': 'INTERNAL', 'name_': 'Q215380', 'id': 1, 'label': 'musical group'}, {'type': 'INTERNAL', 'name_': 'Q9212979', 'id': 2, 'label': 'musical duo'}, {'type': 'INTERNAL', 'name_': 'Q131186', 'id': 3, 'label': 'choir'}, {'type': 'INTERNAL', 'name_': 'Q15920', 'id': 4, 'label': 'Metallica'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q56816954', 'id': 5, 'label': 'heavy metal band'}, {'type': 'INTERNAL', 'name_': 'Q106444275', 'id': 6, 'label': 'Hiroshima'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q105756498', 'id': 7, 'label': 'type of musical ensemble/group'}], 'links': [{'name_': 'P279', 'source': 2, 'target': 1, 'label': 'subclass of'}, {'name_': 'P31', 'source': 2, 'target': 7, 'label': 'instance of'}, {'name_': 'P5008', 'source': 3, 'target': 0, 'label': 'on focus list of Wikimedia project'}, {'name_': 'P31', 'source': 3, 'target': 7, 'label': 'instance of'}, {'name_': 'P5008', 'source': 4, 'target': 0, 'label': 'on focus list of Wikimedia project'}, {'name_': 'P31', 'source': 4, 'target': 5, 'label': 'instance of'}, {'name_': 'P31', 'source': 6, 'target': 1, 'label': 'instance of'}, {'name_': 'P1552', 'source': 6, 'target': 5, 'label': 'has characteristic'}]}