Question: when was the poem o captain my captain written
[{'answer': '1865', 'provenance': [{'wikipedia_id': '2601554', 'title': 'O Captain! My Captain!', 'start_paragraph_id': 1, 'start_character': 65, 'end_paragraph_id': 1, 'end_character': 69, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2601554', 'title': 'O Captain! My Captain!', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 506, 'bleu_score': 0.891390203442, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6025648017812814624}, 'section': 'Section::::Abstract.'}]}]