langchain/llms/huggingface_endpoint.py/HuggingFaceEndpoint/validate_environment
class HuggingFaceEndpoint:    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that api key and python package exists in environment."""
        huggingfacehub_api_token = get_from_dict_or_env(
            values, "huggingfacehub_api_token", "HUGGINGFACEHUB_API_TOKEN"
        )
        try:
            from huggingface_hub.hf_api import HfApi

            try:
                HfApi(
                    endpoint="https://huggingface.co",  # Can be a Private Hub endpoint.
                    token=huggingfacehub_api_token,
                ).whoami()
            except Exception as e:
                raise ValueError(
                    "Could not authenticate with huggingface_hub. "
                    "Please check your API token."
                ) from e

        except ImportError:
            raise ValueError(
                "Could not import huggingface_hub python package. "
                "Please install it with `pip install huggingface_hub`."
            )
        values["huggingfacehub_api_token"] = huggingfacehub_api_token
        return values