Question: what does foo stand for in foo fighters
[{'answer': 'UFO sighting', 'provenance': [{'wikipedia_id': '195883', 'title': 'Foo fighter', 'start_paragraph_id': 2, 'start_character': 160, 'end_paragraph_id': 2, 'end_character': 172, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '195883', 'title': 'Foo fighter', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 324, 'bleu_score': 0.962600167205617, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6800666259303975385}, 'section': 'Section::::Abstract.'}]}]