Question: when was the first ever mcdonald's opened
[{'answer': 'April 15 , 1955', 'provenance': [{'wikipedia_id': '5671742', 'title': "History of McDonald's", 'start_paragraph_id': 8, 'start_character': 812, 'end_paragraph_id': 8, 'end_character': 827, 'bleu_score': 1.0, 'section': 'Section::::Early history.\n'}]}, {'provenance': [{'wikipedia_id': '5671742', 'title': "History of McDonald's", 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 1487, 'bleu_score': 0.969569191207548, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4758478853816427049}, 'section': 'Section::::Early history.\n'}]}]