Question: who does chef's voice in south park
[{'answer': 'Isaac Hayes', 'provenance': [{'wikipedia_id': '2182156', 'title': 'Chef (South Park)', 'start_paragraph_id': 1, 'start_character': 106, 'end_paragraph_id': 1, 'end_character': 117, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2182156', 'title': 'Chef (South Park)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 662, 'bleu_score': 0.936207377410584, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7613623920320407653}, 'section': 'Section::::Abstract.'}]}]