}

    private static String transform(Reader reader) throws IOException {
        final List<String> inputLines = IOUtils.readLines(reader);
        final List<String> outputLines = skipBlanks(transformConfig(inputLines));
        return String.join("\n", outputLines);
    }

    /** Squeeze multiple empty lines into a single line. */
    static List<String> skipBlanks(List<String> lines) {