有用LangChain/LangGraph集成的例子么？

  
  

   
   

    from langchain_core.messages import AnyMessage
   
   
   
   

    from langgraph.errors import GraphRecursionError
   
   
   
   

    from langgraph.prebuilt import create_react_agent
   
   
   
   

    from langchain.tools import tool
   
   
   
   

    from langchain_community.chat_models import QianfanChatEndpoint
   
   
   
   

    
   
   
   
   

    
   
   
   
   

    chat = QianfanChatEndpoint(model="ERNIE-3.5-8K", stream=False)
   
   
   
   

    
   
   
   
   

    
   
   
   
   

    magic_step_num = 1
   
   
   
   

    
   
   
   
   

    @tool
   
   
   
   

    def magic_function(input: int) -> int:
   
   
   
   

        """Applies a magic function to an input."""
   
   
   
   

        global magic_step_num
   
   
   
   

        print(f"Call number: {magic_step_num}")
   
   
   
   

        magic_step_num += 1
   
   
   
   

        return input + magic_step_num
   
   
   
   

    
   
   
   
   

    tools = [magic_function]
   
   
   
   

    
   
   
   
   

    def _modify_messages(messages: list[AnyMessage]):
   
   
   
   

        # Give the agent amnesia, only keeping the original user query
   
   
   
   

        return [("system", "You are a helpful assistant"), messages[0]]
   
   
   
   

    
   
   
   
   

    
   
   
   
   

    app = create_react_agent(model=chat, tools=tools, messages_modifier=_modify_messages)
   
   
   
   

    
   
   
   
   

    #%%
   
   
   
   

    query = "Call the magic function 4 times in sequence with the value 3. You cannot call it multiple times at once."
   
   
   
   

    try:
   
   
   
   

        for step in app.stream({"messages": [("human", query)]}, stream_mode="updates"):
   
   
   
   

            print(step)
   
   
   
   

    except GraphRecursionError as e:
   
   
   
   

        print("Stopping agent prematurely due to triggering stop condition")