langchain/tools/openapi/utils/openapi_utils.py/OpenAPISpec/_get_referenced_request_body
class OpenAPISpec:    def _get_referenced_request_body(
        self, ref: Reference
    ) -> Optional[Union[Reference, RequestBody]]:
        """Get a request body (or nested reference) or err."""
        ref_name = ref.ref.split("/")[-1]
        request_bodies = self._request_bodies_strict
        if ref_name not in request_bodies:
            raise ValueError(f"No request body found for {ref_name}")
        return request_bodies[ref_name]