Question: who is chief in grey's anatomy season 13
[{'answer': 'Miranda Bailey', 'provenance': [{'wikipedia_id': '50555613', 'title': "Grey's Anatomy (season 13)", 'start_paragraph_id': 8, 'start_character': 21, 'end_paragraph_id': 8, 'end_character': 35, 'bleu_score': 1.0, 'section': 'Section::::Plots.\n'}]}, {'provenance': [{'wikipedia_id': '50555613', 'title': "Grey's Anatomy (season 13)", 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 779, 'bleu_score': 0.9843125095516201, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11677931808175780309}, 'section': 'Section::::Plots.\n'}]}]