from llama_index.llms import OpenAI llm = OpenAI(model="gpt-3.5-turbo-0613", temperature=0.0, max_tokens=512) service_context = ServiceContext.from_defaults(llm=llm) index = ListIndex.from_documents(documents, service_context=service_context) query_engine = index.as_query_engine(response_mode="tree_summarize") response = query_engine.query("Summarize the meeting notes. Be sure to include key topics, decisions, and action items.")