Question: what is the main purpose of the league of nations
[{'answer': 'maintain world peace', 'provenance': [{'wikipedia_id': '17926', 'title': 'League of Nations', 'start_paragraph_id': 1, 'start_character': 344, 'end_paragraph_id': 1, 'end_character': 364, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '17926', 'title': 'League of Nations', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 660, 'bleu_score': 0.6064499437050741, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1946612683768851016}, 'section': 'Section::::Abstract.'}]}]