Question: who does the voice of ultron in the avengers
[{'answer': 'James Spader', 'provenance': [{'wikipedia_id': '36484254', 'title': 'Avengers: Age of Ultron', 'start_paragraph_id': 1, 'start_character': 636, 'end_paragraph_id': 1, 'end_character': 648, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '36484254', 'title': 'Avengers: Age of Ultron', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 2030, 'bleu_score': 0.9945129797833611, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7115733201702296632}, 'section': 'Section::::Cast.\n'}]}]