Update app.py

app.py

@@ -42,7 +42,7 @@ class BasicAgent:
         fixed_answer = "This is a default answer."
         print(f"Agent returning answer: {response}")
         
-    def _build_graph():
+    def _build_graph(self):
         self.builder = StateGraph(AgentState)
         self.builder.add_node("assistant", assistant)
         self.builder.add_node("tools", ToolNode(self.tools))