Question: when did league of nations become united nations
[{'answer': '1919', 'provenance': [{'wikipedia_id': '17926', 'title': 'League of Nations', 'start_paragraph_id': 21, 'start_character': 33, 'end_paragraph_id': 21, 'end_character': 37, 'bleu_score': 1.0, 'section': 'Section::::Origins.:Establishment.\n'}]}, {'provenance': [{'wikipedia_id': '17926', 'title': 'League of Nations', 'start_paragraph_id': 21, 'start_character': 0, 'end_paragraph_id': 21, 'end_character': 685, 'bleu_score': 0.9229371361700901, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9938384981174797873}, 'section': 'Section::::Origins.:Establishment.\n'}]}]