Question: whose autobiography has the title a long walk to freedom
[{'answer': 'South African President Nelson Mandela', 'provenance': [{'wikipedia_id': '2108345', 'title': 'Long Walk to Freedom', 'start_paragraph_id': 1, 'start_character': 52, 'end_paragraph_id': 1, 'end_character': 90, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2108345', 'title': 'Long Walk to Freedom', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 660, 'bleu_score': 0.9491353855517691, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18398546226880735024}, 'section': 'Section::::Abstract.'}]}]