langchain/evaluation/qa/eval_chain.py/CotQAEvalChain/from_llm
class CotQAEvalChain:    def from_llm(
        cls, llm: BaseLanguageModel, prompt: PromptTemplate = COT_PROMPT, **kwargs: Any
    ) -> CotQAEvalChain:
        cls._validate_input_vars(prompt)
        return cls(llm=llm, prompt=prompt, **kwargs)