Update graph_builder.py

graph_builder.py

@@ -38,7 +38,7 @@ def build_graph():
 
     graph.add_node("llm", llm_step)
     graph.add_node("formatter", formatter_step)
-    graph.set_entry_point("llm")
+    graph.set_entry_point("llm", input_key="question")
     graph.add_edge("llm", "formatter")
     graph.set_finish_point("formatter")