Question: when did sri lanka leave the british empire
[{'answer': 'February 4 , 1948'}, {'provenance': [{'wikipedia_id': '3253596', 'title': 'Sri Lankan independence movement', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 554, 'bleu_score': 0.833839192119674, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5335201661243422713}, 'section': 'Section::::Abstract.'}]}]