Question: when did the spitfire go out of service
[{'answer': '1 January 1951', 'provenance': [{'wikipedia_id': '15630676', 'title': 'Supermarine Spitfire operational history', 'start_paragraph_id': 3, 'start_character': 238, 'end_paragraph_id': 3, 'end_character': 252, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '15630676', 'title': 'Supermarine Spitfire operational history', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 252, 'bleu_score': 0.9354452495609911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14419515804650502487}, 'section': 'Section::::Abstract.'}]}]