Question: who is brad pitt playing in war machine
[{'answer': 'General Glen McMahon', 'provenance': [{'wikipedia_id': '47496109', 'title': 'War Machine (film)', 'start_paragraph_id': 4, 'start_character': 33, 'end_paragraph_id': 4, 'end_character': 53, 'bleu_score': 1.0, 'section': 'Section::::Plot.\n'}]}, {'provenance': [{'wikipedia_id': '47496109', 'title': 'War Machine (film)', 'start_paragraph_id': 13, 'start_character': 0, 'end_paragraph_id': 13, 'end_character': 240, 'bleu_score': 0.948006874591591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1487220801140226550}, 'section': 'Section::::Cast.\n'}]}]