Update app.py

app.py

@@ -1,10 +1,13 @@
 import streamlit as st
 import textgrad as tg
 
+
 tg.set_backward_engine("gpt-4o", override=True)
 
 # Step 1: Get an initial response from an LLM.
-model = tg.BlackboxLLM("gpt-4o")
+engine = tg.get_engine(engine_name='gpt-4o')
+model = tg.BlackboxLLM(engine)
+
 question_string = ("If it takes 1 hour to dry 25 shirts under the sun, "
                    "how long will it take to dry 30 shirts under the sun? "
                    "Reason step by step")