Question: who played sirius black in prisoner of azkaban
[{'answer': 'Gary Oldman', 'provenance': [{'wikipedia_id': '667371', 'title': 'Harry Potter and the Prisoner of Azkaban (film)', 'start_paragraph_id': 2, 'start_character': 212, 'end_paragraph_id': 2, 'end_character': 223, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '667371', 'title': 'Harry Potter and the Prisoner of Azkaban (film)', 'start_paragraph_id': 21, 'start_character': 0, 'end_paragraph_id': 21, 'end_character': 504, 'bleu_score': 0.569545799365888, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7036688342341981772}, 'section': 'Section::::Cast.\n'}]}]