langchain/llms/replicate.py/Replicate/validate_environment
class Replicate:    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that api key and python package exists in environment."""
        replicate_api_token = get_from_dict_or_env(
            values, "REPLICATE_API_TOKEN", "REPLICATE_API_TOKEN"
        )
        values["replicate_api_token"] = replicate_api_token
        return values