langchain/chains/llm.py/LLMChain/_acall
class LLMChain:    async def _acall(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[AsyncCallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        response = await self.agenerate([inputs], run_manager=run_manager)
        return self.create_outputs(response)[0]