Question: when did the practice of book burning start
[{'answer': 'the 7th century BCE', 'provenance': [{'wikipedia_id': '152534', 'title': 'Book burning', 'start_paragraph_id': 11, 'start_character': 43, 'end_paragraph_id': 11, 'end_character': 62, 'bleu_score': 1.0, 'section': 'Section::::Historical background.:7th century BCE.\n'}]}, {'provenance': [{'wikipedia_id': '152534', 'title': 'Book burning', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 190, 'bleu_score': 0.890173211813112, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16961859873816027193}, 'section': 'Section::::Historical background.:7th century BCE.\n'}]}]