Question: when does it's always sunny in philadelphia season 13 start
[{'answer': 'September 5 , 2018', 'provenance': [{'wikipedia_id': '57905879', 'title': "It's Always Sunny in Philadelphia (season 13)", 'start_paragraph_id': 1, 'start_character': 119, 'end_paragraph_id': 1, 'end_character': 137, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '57905879', 'title': "It's Always Sunny in Philadelphia (season 13)", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 136, 'bleu_score': 0.910879922930628, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7236263384479976491}, 'section': 'Section::::Abstract.'}]}]