private static Optional<TensorFunction<Reference>> importExpression(IntermediateOperation operation, ImportedModel model) {
        if (model.expressions().containsKey(operation.name())) {
            return operation.function();
        }
        if (operation.type().isEmpty()) {
            return Optional.empty();
        }
        if (operation.isConstant()) {
            return importConstant(operation, model);
        }
        importExpressionInputs(operation, model);
        importRankingExpression(operation, model);
        importArgumentExpression(operation, model);
        importFunctionExpression(operation, model);

        return operation.function();
    }
Convert intermediate representation to Vespa ranking expressions.
model-integration/src/main/java/ai/vespa/rankingexpression/importer/ModelImporter.java