langchain/tools/openapi/utils/openapi_utils.py/OpenAPISpec/_get_referenced_parameter
class OpenAPISpec:    def _get_referenced_parameter(self, ref: Reference) -> Union[Parameter, Reference]:
        """Get a parameter (or nested reference) or err."""
        ref_name = ref.ref.split("/")[-1]
        parameters = self._parameters_strict
        if ref_name not in parameters:
            raise ValueError(f"No parameter found for {ref_name}")
        return parameters[ref_name]