Question: who played keyboard on don't let me down
[{'answer': 'McCartney', 'provenance': [{'wikipedia_id': '2701307', 'title': "Don't Let Me Down (Beatles song)", 'start_paragraph_id': 1, 'start_character': 171, 'end_paragraph_id': 1, 'end_character': 180, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2701307', 'title': "Don't Let Me Down (Beatles song)", 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 676, 'bleu_score': 0.8734427131228331, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12236459749888969641}, 'section': 'Section::::Composition.\n'}]}]