from langchain_community.callbacks.manager import get_openai_callback

llm = ChatOpenAI(
    model="gpt-4o-mini",
    temperature=0,
    stream_usage=True,
)

with get_openai_callback() as cb:
    result = llm.invoke("Tell me a joke")
    print(cb)
//Tokens Used: 27
    Prompt Tokens: 11
    Completion Tokens: 16
Successful Requests: 1
Total Cost (USD): $2.95e-05


with get_openai_callback() as cb:
    result = graph.invoke({"messages":["How's the weather in Beijing"]})
    print(668, result)
    print(236, cb)
    print(569, cb.total_tokens)
//236 Tokens Used: 3715
        Prompt Tokens: 3560
                Prompt Tokens Cached: 0
        Completion Tokens: 155
                Reasoning Tokens: 0
Successful Requests: 6
Total Cost (USD): $0.0006269999999999998
569 3715