langchain/experimental/plan_and_execute/executors/base.py/ChainExecutor/astep
class ChainExecutor:    async def astep(
        self, inputs: dict, callbacks: Callbacks = None, **kwargs: Any
    ) -> StepResponse:
        """Take step."""
        response = await self.chain.arun(**inputs, callbacks=callbacks)
        return StepResponse(response=response)