Question: when did bojack horseman season 4 come out
[{'answer': 'September 8 , 2017', 'provenance': [{'wikipedia_id': '43617969', 'title': 'BoJack Horseman', 'start_paragraph_id': 18, 'start_character': 74, 'end_paragraph_id': 18, 'end_character': 92, 'bleu_score': 1.0, 'section': 'Section::::Music.:Soundtrack.\n'}]}]