langchain/chains/sql_database/base.py/SQLDatabaseChain/raise_deprecation
class SQLDatabaseChain:    def raise_deprecation(cls, values: Dict) -> Dict:
        if "llm" in values:
            warnings.warn(
                "Directly instantiating an SQLDatabaseChain with an llm is deprecated. "
                "Please instantiate with llm_chain argument or using the from_llm "
                "class method."
            )
            if "llm_chain" not in values and values["llm"] is not None:
                database = values["database"]
                prompt = values.get("prompt") or SQL_PROMPTS.get(
                    database.dialect, PROMPT
                )
                values["llm_chain"] = LLMChain(llm=values["llm"], prompt=prompt)
        return values