Who was the husband to Catherine the Great and the son of Charles Frederick?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q34266', 'id': 0, 'label': 'Russian Empire'}, {'type': 'INTERNAL', 'name_': 'Q254106', 'id': 1, 'label': 'Crimean War'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q36450', 'id': 2, 'label': 'Catherine II of Russia'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q5077830', 'id': 3, 'label': 'Charles Frederick'}], 'links': [{'name_': 'P17', 'source': 0, 'target': 0, 'label': 'country'}, {'name_': 'P793', 'source': 0, 'target': 1, 'label': 'significant event'}, {'name_': 'P35', 'source': 0, 'target': 2, 'label': 'head of state'}, {'name_': 'P607', 'source': 3, 'target': 1, 'label': 'conflict'}]}