Question: who is the actor that plays robbie rotten
[{'answer': 'Stefán Karl Stefánsson', 'provenance': [{'wikipedia_id': '2745936', 'title': 'Stefán Karl Stefánsson', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 22, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]