FunctionNameToFunctionDefMap(const FunctionDefLibrary& library);

// Finds the "signatures" object in the object graph, and fills a mapping of
// each signature's name to the corresponding function's node in the object
// graph.
Status GetSignaturesMap(const SavedObjectGraph& saved_objects,
                        gtl::FlatMap<std::string, int>* signatures_map);

// Validates the `saved_function`.