What river flows through Nebraska and is the longest river in the United States?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q30', 'id': 0, 'label': 'United States of America'}, {'type': 'INTERNAL', 'name_': 'Q13442814', 'id': 1, 'label': 'scholarly article'}, {'type': 'INTERNAL', 'name_': 'Q953', 'id': 2, 'label': 'Zambia'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q1553', 'id': 3, 'label': 'Nebraska'}, {'type': 'INTERNAL', 'name_': 'Q104436116', 'id': 4, 'label': 'A new, unusual castorid (Rodentia) from the earliest Miocene of Nebraska'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q113061049', 'id': 5, 'label': 'The Mississippi River'}], 'links': [{'name_': 'P17', 'source': 0, 'target': 0, 'label': 'country'}, {'name_': 'P530', 'source': 0, 'target': 2, 'label': 'diplomatic relation'}, {'name_': 'P150', 'source': 0, 'target': 3, 'label': 'contains the administrative territorial entity'}, {'name_': 'P1963', 'source': 1, 'target': 2, 'label': 'properties for this type'}, {'name_': 'P530', 'source': 2, 'target': 0, 'label': 'diplomatic relation'}, {'name_': 'P17', 'source': 2, 'target': 2, 'label': 'country'}, {'name_': 'P17', 'source': 3, 'target': 0, 'label': 'country'}, {'name_': 'P31', 'source': 4, 'target': 1, 'label': 'instance of'}, {'name_': 'P921', 'source': 4, 'target': 3, 'label': 'main subject'}, {'name_': 'P31', 'source': 5, 'target': 1, 'label': 'instance of'}]}