Question: who plays johnny cochran in american crime story
[{'answer': 'Courtney B. Vance', 'provenance': [{'wikipedia_id': '44052917', 'title': 'American Crime Story', 'start_paragraph_id': 7, 'start_character': 295, 'end_paragraph_id': 7, 'end_character': 312, 'bleu_score': 1.0, 'section': 'Section::::Overview.:"The People v. O. J. Simpson" (2016).\n'}]}]