langchain/chains/natbot/base.py/NatBotChain/from_default
class NatBotChain:    def from_default(cls, objective: str, **kwargs: Any) -> NatBotChain:
        """Load with default LLMChain."""
        llm = OpenAI(temperature=0.5, best_of=10, n=3, max_tokens=50)
        return cls.from_llm(llm, objective, **kwargs)