Question: when did robert louis stevenson write treasure island
[{'answer': '1881', 'provenance': [{'wikipedia_id': '26444', 'title': 'Robert Louis Stevenson', 'start_paragraph_id': 63, 'start_character': 107, 'end_paragraph_id': 63, 'end_character': 111, 'bleu_score': 1.0, 'section': 'Section::::Monuments and commemoration.\n'}]}, {'provenance': [{'wikipedia_id': '26444', 'title': 'Robert Louis Stevenson', 'start_paragraph_id': 63, 'start_character': 0, 'end_paragraph_id': 63, 'end_character': 159, 'bleu_score': 0.9321022168949711, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17931619621572196167}, 'section': 'Section::::Monuments and commemoration.\n'}]}]