langchain/llms/manifest.py/ManifestWrapper/validate_environment
class ManifestWrapper:    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that python package exists in environment."""
        try:
            from manifest import Manifest

            if not isinstance(values["client"], Manifest):
                raise ValueError
        except ImportError:
            raise ValueError(
                "Could not import manifest python package. "
                "Please install it with `pip install manifest-ml`."
            )
        return values