llm_predictor = LLMPredictor(llm=ChatOpenAI(model_name="gpt-3.5-turbo", temperature=0.2))
index = GPTSimpleVectorIndex(docs, llm_predictor=llm_predictor)
index.save_to_disk('./saved_index.json')
loaded_index = GPTSimpleVectorIndex.load_from_disk('./saved_index.json')
loaded_index.llm_predictor._llm.model_name