Question: who sang don't let me down by the beatles
[{'answer': 'John Lennon', 'provenance': [{'wikipedia_id': '2701307', 'title': "Don't Let Me Down (Beatles song)", 'start_paragraph_id': 1, 'start_character': 136, 'end_paragraph_id': 1, 'end_character': 147, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Paul McCartney', 'provenance': [{'wikipedia_id': '2701307', 'title': "Don't Let Me Down (Beatles song)", 'start_paragraph_id': 3, 'start_character': 84, 'end_paragraph_id': 3, 'end_character': 98, 'bleu_score': 1.0, 'section': 'Section::::Composition.\n'}]}, {'answer': 'George Harrison', 'provenance': [{'wikipedia_id': '2701307', 'title': "Don't Let Me Down (Beatles song)", 'start_paragraph_id': 39, 'start_character': 12, 'end_paragraph_id': 39, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::Personnel.\n'}]}]