List<Pair<String, RankingExpression>> readFunctions() {
            try {
                ApplicationFile file = application.getFile(modelFiles.functionsPath());
                if ( ! file.exists()) return List.of();

                List<Pair<String, RankingExpression>> functions = new ArrayList<>();
                try (BufferedReader reader = new BufferedReader(file.createReader())) {
                    String line;
                    while (null != (line = reader.readLine())) {
                        String[] parts = line.split("\t");
                        String name = parts[0];
                        try {
                            RankingExpression expression = new RankingExpression(parts[0], parts[1]);
                            functions.add(new Pair<>(name, expression));
                        } catch (ParseException e) {
                            throw new IllegalStateException("Could not parse " + name, e);
                        }
                    }
                    return functions;
                }
            }
            catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }
Reads the previously stored function expressions for these arguments
config-model/src/main/java/com/yahoo/vespa/model/ml/ConvertedModel.java