openai = GPTVectorStoreIndex.from_documents([], service_context=ServiceContext.from_defaults())
openai = openai.as_query_engine()
response = openai.query("tell me about narendra modi")
the above does not work. it gives None. π£
can you please guide me how to build a q/a query_engine_tool for answering quesitons without context
which I can pass it query_engine_tools parameter of RouterQueryEngine