Question: when did the dell latitude e6540 come out
[{'answer': '2013', 'provenance': [{'wikipedia_id': '2762802', 'title': 'Dell Latitude', 'start_paragraph_id': 84, 'start_character': 42, 'end_paragraph_id': 84, 'end_character': 46, 'bleu_score': 1.0, 'section': 'Section::::Previous Models.:Exx50 Models (2015).\n'}]}]