// graph.
Status GetSignaturesMap(const SavedObjectGraph& saved_objects,
                        gtl::FlatMap<std::string, int>* signatures_map);

// Validates the `saved_function`.
Status ValidateSingleConcreteFunction(const SavedFunction& saved_function);

// Walks through the SavedObjectGraph in metagraph, and restores all nodes
// (except "UserDefinedObjects") with their corresponding type in
// "PartiallyRevivedObjects".