Question: when does the 13 days of halloween start on freeform
[{'answer': 'October 19 , 2017'}, {'provenance': [{'wikipedia_id': '29840829', 'title': '31 Nights of Halloween', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 615, 'bleu_score': 0.73509694993102, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11710470464827986717}, 'section': 'Section::::Abstract.'}]}]