private static void importExpressions(IntermediateGraph graph, ImportedModel model) {
        for (ImportedModel.Signature signature : model.signatures().values()) {
            for (String outputName : signature.outputs().values()) {
                try {
                    Optional<TensorFunction<Reference>> function = importExpression(graph.get(outputName), model);
                    if (function.isEmpty()) {
                        signature.skippedOutput(outputName, "No valid output function could be found.");
                    }
                }
                catch (IllegalArgumentException e) {
                    signature.skippedOutput(outputName, Exceptions.toMessageString(e));
                }
            }
        }
    }
Convert intermediate representation to Vespa ranking expressions.
model-integration/src/main/java/ai/vespa/rankingexpression/importer/ModelImporter.java