Question: what do the letters in nato stand for
[{'answer': 'North Atlantic Treaty Organization', 'provenance': [{'wikipedia_id': '21133', 'title': 'NATO', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 38, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21133', 'title': 'NATO', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 271, 'bleu_score': 0.5727174953210891, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7119570609605227448}, 'section': 'Section::::Abstract.'}]}]