Question: who played in the men's semi final in wimbledon in 2015
[{'answer': 'Novak Djokovic', 'provenance': [{'wikipedia_id': '46928555', 'title': "2015 Wimbledon Championships – Men's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Richard Gasquet'}, {'answer': 'Andy Murray'}, {'answer': 'Roger Federer', 'provenance': [{'wikipedia_id': '46928555', 'title': "2015 Wimbledon Championships – Men's Singles", 'start_paragraph_id': 1, 'start_character': 90, 'end_paragraph_id': 1, 'end_character': 103, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]