Question: when did game of thrones season 8 start filming
[{'answer': 'October 23 , 2017', 'provenance': [{'wikipedia_id': '53470508', 'title': 'Game of Thrones (season 8)', 'start_paragraph_id': 61, 'start_character': 380, 'end_paragraph_id': 61, 'end_character': 400, 'bleu_score': 1.0, 'section': 'Section::::Production.:Filming.\n'}]}]