langchain mein if chabot bana ho but like uska code invoke na support

 from transformers import AutoTokenizer, AutoModelForCausalLM

from langchain_core.runnables import RunnableLambda

model_name = "Qwen/Qwen3-0.6B"

tokenizer = AutoTokenizer.from_pretrained(model_name)

model = AutoModelForCausalLM.from_pretrained(

    model_name,

    device_map="auto"

)

def generate_response(user_input):

    messages = [

        {"role": "user", "content": user_input}

    ]

    text = tokenizer.apply_chat_template(

        messages,

        tokenize=False,

        add_generation_prompt=True,

        enable_thinking=True

    )

    inputs = tokenizer(text, return_tensors="pt").to(model.device)

    outputs = model.generate(

        **inputs,

        max_new_tokens=200

    )

    response = tokenizer.decode(

        outputs[0][inputs.input_ids.shape[1]:],

        skip_special_tokens=True

    )

    return response

llm = RunnableLambda(generate_response)

print(llm.invoke("Who are Eldians in AOT?"))