Question: when did britain vote to leave the eu
[{'answer': '23 June 2016', 'provenance': [{'wikipedia_id': '41688778', 'title': 'Brexit', 'start_paragraph_id': 1, 'start_character': 155, 'end_paragraph_id': 1, 'end_character': 167, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]