Question: when did the battle of vimy ridge happen
[{'answer': '9 to 12 April 1917', 'provenance': [{'wikipedia_id': '70435', 'title': 'Battle of Vimy Ridge', 'start_paragraph_id': 1, 'start_character': 290, 'end_paragraph_id': 1, 'end_character': 308, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '70435', 'title': 'Battle of Vimy Ridge', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 558, 'bleu_score': 0.955468993395951, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2383140436745320707}, 'section': 'Section::::Abstract.'}]}]