Question: when does derek shepherd die on grey's anatomy
[{'answer': 'season 11', 'provenance': [{'wikipedia_id': '7619908', 'title': 'Derek Shepherd', 'start_paragraph_id': 12, 'start_character': 3, 'end_paragraph_id': 12, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Storyline.\n'}]}, {'provenance': [{'wikipedia_id': '7619908', 'title': 'Derek Shepherd', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 863, 'bleu_score': 0.936477622595786, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11517901416356061219}, 'section': 'Section::::Storyline.\n'}]}]