Question: when did it become law that a president can only serve 2 terms
[{'answer': 'March 24 , 1947', 'provenance': [{'wikipedia_id': '70132', 'title': 'Twenty-second Amendment to the United States Constitution', 'start_paragraph_id': 16, 'start_character': 71, 'end_paragraph_id': 16, 'end_character': 86, 'bleu_score': 1.0, 'section': 'Section::::Proposal and ratification.:Proposal in Congress.\n'}]}, {'provenance': [{'wikipedia_id': '70132', 'title': 'Twenty-second Amendment to the United States Constitution', 'start_paragraph_id': 2, 'start_character': 170, 'end_paragraph_id': 2, 'end_character': 797, 'bleu_score': 0.501335430621355, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1778476205850622407}, 'section': 'Section::::Abstract.'}]}]