Question: what season does izzie stevens leave grey's anatomy
[{'answer': 'the sixth season', 'provenance': [{'wikipedia_id': '7687022', 'title': 'Izzie Stevens', 'start_paragraph_id': 2, 'start_character': 705, 'end_paragraph_id': 2, 'end_character': 721, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7687022', 'title': 'Izzie Stevens', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1190, 'bleu_score': 0.9770487830978931, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4829937485993283750}, 'section': 'Section::::Abstract.'}]}]