changed issue in app

app.py

@@ -17,7 +17,7 @@ class BasicAgent:
         print("BasicAgent initialized.")
     def __call__(self, question: str) -> str:
         messages = [HumanMessage(content=question)]
-        response = self.graph.invoke({"messages": messages})
+        response = self.agent.invoke({"messages": messages})
         fixed_answer = response['messages'][-1].content[16:]
         print(f"Agent returning fixed answer: {fixed_answer}")
         return fixed_answer