Question: who won the us open men’s singles title on 11th september 2016
[{'answer': 'Stan Wawrinka', 'provenance': [{'wikipedia_id': '51042165', 'title': "2016 US Open – Men's Singles", 'start_paragraph_id': 1, 'start_character': 68, 'end_paragraph_id': 1, 'end_character': 81, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '51042165', 'title': "2016 US Open – Men's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 540, 'bleu_score': 0.651478827434262, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 558307406739935279}, 'section': 'Section::::Abstract.'}]}]