Update agent.py

agent.py

@@ -2,7 +2,7 @@ from typing import TypedDict, Annotated
 from tool import add, substract, multiply, divide, DuckDuckGoSearchTool, WikipediaSearchTool, ArxivSearchTool, PubmedSearchTool
 
 from langgraph.graph.message import add_messages
-from langchain_core.messages import AnyMessage, HumanMessage, AIMessage
+from langchain_core.messages import AnyMessage, SystemMessage, HumanMessage, AIMessage
 from langgraph.graph import StateGraph, START, END, MessagesState
 from langgraph.prebuilt import ToolNode, tools_condition
 from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace