Question: when did salvador dali paint the persistence of memory
[{'answer': '1931', 'provenance': [{'wikipedia_id': '370807', 'title': 'The Persistence of Memory', 'start_paragraph_id': 1, 'start_character': 34, 'end_paragraph_id': 1, 'end_character': 38, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]