Question: who played the sith lord in return of the jedi
[{'answer': 'Ian McDiarmid', 'provenance': [{'wikipedia_id': '18581372', 'title': 'Ian McDiarmid', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]