WikipediaReader = download_loader("WikipediaReader")

loader = WikipediaReader()
pages = ['Nicolas_Cage', 'The_Best_of_Times_(1981_film)', 'Leonardo DiCaprio']
documents = loader.load_data(pages=pages, auto_suggest=False, redirect = False)

llm = OpenAI(temperature=0, model="gpt-3.5-turbo")
gpt3 = OpenAI(temperature=0, model="text-davinci-003")

embed_model = OpenAIEmbedding(model= OpenAIEmbeddingModelType.TEXT_EMBED_ADA_002)
service_context_gpt3 = ServiceContext.from_defaults(llm=gpt3, chunk_size = 256, chunk_overlap=0, embed_model=embed_model)

index = VectorStoreIndex.from_documents(documents, service_context=service_context_gpt3)
retriever = index.as_retriever(similarity_top_k=3)