code: public static Dataset<String, String> readSVMLightFormat(String filename, List<String> lines) {
      return readSVMLightFormat(filename, new HashIndex<String>(), new HashIndex<String>(), lines);
    }
docs: Constructs a Dataset by reading in a file in SVM light format.
  The lines parameter is filled with the lines of the file for further processing
  (if lines is null, it is assumed no line information is desired)