langchain/llms/huggingface_hub.py/HuggingFaceHub/_call
class HuggingFaceHub:    def _call(
        self,
        prompt: str,
        stop: Optional[List[str]] = None,
        run_manager: Optional[CallbackManagerForLLMRun] = None,
    ) -> str:
        """Call out to HuggingFace Hub's inference endpoint.

        Args:
            prompt: The prompt to pass into the model.
            stop: Optional list of stop words to use when generating.

        Returns:
            The string generated by the model.

        Example:
            .. code-block:: python

                response = hf("Tell me a joke.")
        """
        _model_kwargs = self.model_kwargs or {}
        response = self.client(inputs=prompt, params=_model_kwargs)
        if "error" in response:
            raise ValueError(f"Error raised by inference API: {response['error']}")
        if self.client.task == "text-generation":
            # Text generation return includes the starter text.
            text = response[0]["generated_text"][len(prompt) :]
        elif self.client.task == "text2text-generation":
            text = response[0]["generated_text"]
        elif self.client.task == "summarization":
            text = response[0]["summary_text"]
        else:
            raise ValueError(
                f"Got invalid task {self.client.task}, "
                f"currently only {VALID_TASKS} are supported"
            )
        if stop is not None:
            # This is a bit hacky, but I can't figure out a better way to enforce
            # stop tokens when making calls to huggingface_hub.
            text = enforce_stop_tokens(text, stop)
        return text