Question: who won the 2017 men's singles australian open tennis tournament
[{'answer': 'Roger Federer', 'provenance': [{'wikipedia_id': '52071240', 'title': "2017 Australian Open – Men's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '52071240', 'title': "2017 Australian Open – Men's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 376, 'bleu_score': 0.7106037141405721, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15692197705796705846}, 'section': 'Section::::Abstract.'}]}]