Update app.py

app.py

@@ -55,6 +55,7 @@ def query_llm(retriever, query):
         llm=OpenAIChat(),
         retriever=retriever,
         return_source_documents=True,
+        chain_type="refine",
     )
     relevant_docs = retriever.get_relevant_documents(query)
     result = qa_chain({"question": query, "chat_history": st.session_state.messages})