Question: who plays the ancient one in dr strange
[{'answer': 'Tilda Swinton', 'provenance': [{'wikipedia_id': '2173507', 'title': 'Ancient One', 'start_paragraph_id': 2, 'start_character': 86, 'end_paragraph_id': 2, 'end_character': 99, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]