public static void printResult(String result, String ...spacer_str) {
        String spacer = getSingleDefault(spacer_str, "-");
        
        int longest_line_length = 1;
        
        String[] lines = result.split("\n");
        for (int l=0; l<lines.length; l++) {
            longest_line_length = Math.max(longest_line_length, lines[l].length());
        }
        
        String header_footer = multiplyString(spacer, longest_line_length);
        
        System.out.println(header_footer);
        System.out.println(result);
        System.out.println(header_footer);
    }