langchain/llms/huggingface_hub.py/HuggingFaceHub/validate_environment
class HuggingFaceHub:    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.inference_api import InferenceApi

            repo_id = values["repo_id"]
            client = InferenceApi(
                repo_id=repo_id,
                token=huggingfacehub_api_token,
                task=values.get("task"),
            )
            if client.task not in VALID_TASKS:
                raise ValueError(
                    f"Got invalid task {client.task}, "
                    f"currently only {VALID_TASKS} are supported"
                )
            values["client"] = client
        except ImportError:
            raise ValueError(
                "Could not import huggingface_hub python package. "
                "Please install it with `pip install huggingface_hub`."
            )
        return values