Question: when did the washington senators become the minnesota twins
[{'answer': '1960', 'provenance': [{'wikipedia_id': '20050', 'title': 'Minnesota Twins', 'start_paragraph_id': 5, 'start_character': 47, 'end_paragraph_id': 5, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::Team history.\n'}]}, {'provenance': [{'wikipedia_id': '20050', 'title': 'Minnesota Twins', 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 839, 'bleu_score': 0.985764216565234, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5426264455082205933}, 'section': 'Section::::Team history.:Washington Nationals/Senators: 1901–1960.\n'}]}]