The chain output.
        Example:
            .. code-block:: python
                # Suppose we have a single-input chain that takes a 'question' string:
                await chain.arun("What's the temperature in Boise, Idaho?")
                # -> "The temperature in Boise is..."
                # Suppose we have a multi-input chain that takes a 'question' string
                # and 'context' string:
                question = "What's the temperature in Boise, Idaho?"
                context = "Weather report for Boise, Idaho on 07/03/23..."
                await chain.arun(question=question, context=context)
                # -> "The temperature in Boise is..."
        """
        if len(self.output_keys) != 1:
            raise ValueError(
                f"`run` not supported when there is not exactly "
                f"one output key. Got {self.output_keys}."
            )
        elif args and not kwargs:
            if len(args) != 1:
                raise ValueError("`run` supports only one positional argument.")
            return (
                await self.acall(
                    args[0], callbacks=callbacks, tags=tags, metadata=metadata
                )
            )[self.output_keys[0]]
        if kwargs and not args:
            return (
                await self.acall(
                    kwargs, callbacks=callbacks, tags=tags, metadata=metadata
                )
            )[self.output_keys[0]]
        raise ValueError(
            f"`run` supported with either positional arguments or keyword arguments"
            f" but not both. Got args: {args} and kwargs: {kwargs}."
        )
[docs]    def dict(self, **kwargs: Any) -> Dict:
        """Dictionary representation of chain.