Update app.py

app.py

@@ -69,10 +69,11 @@ def doc_preprocessing():
 # doc_db = embedding_db()
 
 def retrieval_answer(query):
+    chat_model = ChatOpenAI()  # Create the LLM instance
     qa = RetrievalQA.from_chain_type(
-    llm=llm, 
-    chain_type='stuff',
-    retriever=doc_db.as_retriever(),
+        llm=chat_model,   # Pass the chat_model instance 
+        chain_type='stuff',
+        retriever=doc_db.as_retriever(),
     )
     query = query
     result = qa.run(query)