Question: who plays gus waters in the fault in our stars
[{'answer': 'Ansel Elgort', 'provenance': [{'wikipedia_id': '39355524', 'title': 'Ansel Elgort', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]