Question: when did rome become an empire and stop being a republic
[{'answer': '27 BC', 'provenance': [{'wikipedia_id': '25816', 'title': 'Roman Republic', 'start_paragraph_id': 1, 'start_character': 164, 'end_paragraph_id': 1, 'end_character': 169, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '25816', 'title': 'Roman Republic', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 355, 'bleu_score': 0.7908146078530001, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12165526624646432773}, 'section': 'Section::::Abstract.'}]}]