Question: which soviet leader was known as a reformer
[{'answer': 'Nikita Sergeyevich Khrushchev', 'provenance': [{'wikipedia_id': '42558', 'title': 'Nikita Khrushchev', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 29, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '42558', 'title': 'Nikita Khrushchev', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 653, 'bleu_score': 0.902864214637741, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9441289661103322018}, 'section': 'Section::::Abstract.'}]}]