Question: who won the roller derby world cup 2018
[{'answer': 'USA Roller Derby', 'provenance': [{'wikipedia_id': '55088940', 'title': '2018 Roller Derby World Cup', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 16, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '55088940', 'title': '2018 Roller Derby World Cup', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 89, 'bleu_score': 0.850733133512352, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4611836666714958836}, 'section': 'Section::::Abstract.'}]}]