Question: when did matt walst join three days grace
[{'answer': '2013', 'provenance': [{'wikipedia_id': '576533', 'title': 'Three Days Grace', 'start_paragraph_id': 1, 'start_character': 347, 'end_paragraph_id': 1, 'end_character': 351, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '576533', 'title': 'Three Days Grace', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 486, 'bleu_score': 0.8849881880782371, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 269054414395238793}, 'section': 'Section::::Abstract.'}]}]