Question: when was the last time a nuclear bomb was used
[{'answer': 'August 9 , 1945', 'provenance': [{'wikipedia_id': '36880', 'title': 'Nuclear warfare', 'start_paragraph_id': 16, 'start_character': 187, 'end_paragraph_id': 16, 'end_character': 202, 'bleu_score': 1.0, 'section': 'Section::::History.:1940s.:Atomic bombings of Hiroshima and Nagasaki.\n'}]}, {'provenance': [{'wikipedia_id': '36880', 'title': 'Nuclear warfare', 'start_paragraph_id': 16, 'start_character': 0, 'end_paragraph_id': 16, 'end_character': 280, 'bleu_score': 0.9611463610973231, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14188153642321999857}, 'section': 'Section::::History.:1940s.:Atomic bombings of Hiroshima and Nagasaki.\n'}]}]