Question: who plays mackenzie in the movie the shack
[{'answer': 'Sam Worthington', 'provenance': [{'wikipedia_id': '46929116', 'title': 'The Shack (2017 film)', 'start_paragraph_id': 1, 'start_character': 217, 'end_paragraph_id': 1, 'end_character': 232, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]