langchain/llms/cohere.py/Cohere/validate_environment
class Cohere:    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that api key and python package exists in environment."""
        cohere_api_key = get_from_dict_or_env(
            values, "cohere_api_key", "COHERE_API_KEY"
        )
        try:
            import cohere

            values["client"] = cohere.Client(cohere_api_key)
        except ImportError:
            raise ImportError(
                "Could not import cohere python package. "
                "Please install it with `pip install cohere`."
            )
        return values