Question: who is the highest ranking air force officer
[{'answer': 'General David L. Goldfein', 'provenance': [{'wikipedia_id': '736842', 'title': 'Chief of Staff of the United States Air Force', 'start_paragraph_id': 3, 'start_character': 47, 'end_paragraph_id': 3, 'end_character': 72, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '736842', 'title': 'Chief of Staff of the United States Air Force', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 72, 'bleu_score': 0.861173529963367, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4425652371233439934}, 'section': 'Section::::Abstract.'}]}]