Update app.py

app.py

@@ -7,7 +7,7 @@ from langgraph.prebuilt import ToolNode, tools_condition
 from langgraph.graph.message import add_messages
 from typing import List, Dict
 from typing import TypedDict, Annotated
-from langchain_core.messages import AnyMessage, HumanMessage
+from langchain_core.messages import AnyMessage, HumanMessage, SystemMessage
 from langgraph.graph import START, StateGraph
 from langchain_google_genai import ChatGoogleGenerativeAI
 from ToolSet import toolset