I have two tool about add and multiply, it work find when in seperate, but it occur error when i ask like "1 + 2 and 3 * 4"

[modestme]

from typing import Annotated

from langchain_core.tools import tool
from langgraph.constants import END, START
from typing_extensions import TypedDict
from langgraph.graph import StateGraph
from langgraph.graph.message import add_messages
from langchain_openai import ChatOpenAI
from langgraph.prebuilt import ToolNode, tools_condition
from langgraph.checkpoint.sqlite import SqliteSaver
from langchain_core.pydantic_v1 import BaseModel, Field

class State(TypedDict):
messages: Annotated[list, add_messages]

@tool
def add(first_int: int, second_int: int) -> int:
"""
Add two integers together.

"""
return first_int + second_int

@tool
def multiply(first_int: int, second_int: int) -> int:
"""
Multiply two integers together in more fast way.

"""
return first_int * second_int

class AddTask(BaseModel):
"""Add two integers together."""

first_int: int = Field(description="frist num")

second_int: int = Field(description="second num")

class MultiplyTask(BaseModel):
"""multiply two integers together."""

first_int: int = Field(description="frist num")

second_int: int = Field(description="second num")

tools = [AddTask, MultiplyTask]
llm = ChatOpenAI()
llm_with_tools = llm.bind_tools(tools)

def chatbot(state: State):
message = {"messages": [llm_with_tools.invoke(state["messages"])]}
return message

"""

1. 定义一个继承 TypedDict 的 类作为图的状态类，整个图的节点通过该类的共享变量进行通信
2. StateGraph(State)
3. 通过 add_node 添加 function 或 runnable 节点
4. 通过 add_edge 为节点添加确定的边
5. 通过 add_conditional_edges 为节点添加有条件的边
6. 通过 compile 生成 CompiledStateGraph graph
7. 调用 graph.invoke/stream
   """
   graph_builder = StateGraph(State)

graph_builder.add_node("chatbot", chatbot)

add_node = ToolNode(tools=[AddTask])
multiply_node = ToolNode(tools=[MultiplyTask])
graph_builder.add_node("add", add_node)
graph_builder.add_node("multiply", multiply_node)

-> list[Literal["add", "multiply", "end"]]

def route_tools(state: State):
next_node = tools_condition(state)
# If no tools are invoked, return to the user
if next_node == END:
return END

tool_calls = state["messages"][-1].tool_calls
target = []
if tool_calls:
    for call in tool_calls:
        if call["name"] == AddTask.__name__:
            target += ["add"]
        elif call["name"] == MultiplyTask.__name__:
            target += ["multiply"]
    return target
return [END]

graph_builder.add_edge(START, "chatbot")
graph_builder.add_conditional_edges(
"chatbot",
route_tools,
)

graph_builder.add_edge("add", "chatbot")
graph_builder.add_edge("multiply", "chatbot")
memory = SqliteSaver.from_conn_string(":memory:")

memory = MemorySaver()

graph = graph_builder.compile(checkpointer=memory)
config = {"configurable": {"thread_id": "1"}}

print(graph.get_graph().draw_mermaid())

def _print_event(event: dict, _printed: set, max_length=1500):
message = event.get("messages")
if message:
if isinstance(message, list):
message = message[-1]
if message.id not in _printed:
msg_repr = message.pretty_repr(html=True)
if len(msg_repr) > max_length:
msg_repr = msg_repr[:max_length] + " ... (truncated)"
print(msg_repr)
_printed.add(message.id)

while True:
user_input = input("User: ")
if user_input.lower() in ["quit", "exit", "q"]:
print("Goodbye!")
break
_printed = set()
events = graph.stream(
{"messages": ("user", user_input)}, config, stream_mode="values"
)
for event in events:
_print_event(event, _printed)