Question: when did the cubist movement start and end
[{'answer': '1906', 'provenance': [{'wikipedia_id': '37803', 'title': 'Cubism', 'start_paragraph_id': 2, 'start_character': 418, 'end_paragraph_id': 2, 'end_character': 422, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1921', 'provenance': [{'wikipedia_id': '37803', 'title': 'Cubism', 'start_paragraph_id': 5, 'start_character': 877, 'end_paragraph_id': 5, 'end_character': 881, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '37803', 'title': 'Cubism', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 1124, 'bleu_score': 0.9890406822930451, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2334963845597452113}, 'section': 'Section::::History.\n'}]}]