Question: when did the buffalo nickel stop being made
[{'answer': 'April 1938', 'provenance': [{'wikipedia_id': '4055812', 'title': 'Buffalo nickel', 'start_paragraph_id': 26, 'start_character': 519, 'end_paragraph_id': 26, 'end_character': 529, 'bleu_score': 1.0, 'section': 'Section::::Release and production.\n'}]}, {'provenance': [{'wikipedia_id': '4055812', 'title': 'Buffalo nickel', 'start_paragraph_id': 26, 'start_character': 0, 'end_paragraph_id': 26, 'end_character': 707, 'bleu_score': 0.9832621206481431, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16474427287123949699}, 'section': 'Section::::Release and production.\n'}]}]