instantiate chain in single line

app.py

@@ -88,8 +88,7 @@ def clear_chat_history():
 st.button('Clear Chat', on_click=clear_chat_history)
 
 # build our chain outside the working body so that its only instantiated once - simply pass it the chat history for chat completion
-chain_builder = ChainBuilder()
-chain = chain_builder.build_chain()
+chain = ChainBuilder().build_chain()
 
 def last_role_is_user():
     return len(st.session_state["messages"]) > 0 and st.session_state["messages"][-1]["role"] == "user"