code: public void toFile(File file, Engine engine,
              InputVariable a, InputVariable b, Reader reader,
              List<OutputVariable> outputVariables) throws IOException {
          BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(
                  new FileOutputStream(file), FuzzyLite.UTF_8));
          try {
              writeScriptExportingDataFrame(engine, writer, a, b, reader, outputVariables);
          } catch (RuntimeException ex) {
              throw ex;
          } catch (IOException ex) {
              throw ex;
          } finally {
              writer.close();
          }
      }
docs: Creates an R script file plotting multiple surfaces based on the input
  stream of values for the two input variables.
  
  @param file is the R script file
  @param engine is the engine to export
  @param a is the first input variable
  @param b is the second input variable
  @param reader is an input stream of data whose lines contain
  space-separated input values
  @param outputVariables are the output variables to create the surface for
  @throws IOException if any error occurs upon writing the file