code: public void toFile(File file, Engine engine,
              InputVariable a, InputVariable b,
              int values, FldExporter.ScopeOfValues scope,
              List<OutputVariable> outputVariables) throws IOException {
          BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(
                  new FileOutputStream(file), FuzzyLite.UTF_8));
          try {
              writeScriptExportingDataFrame(engine, writer, a, b, values, scope, 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 a data frame
  generated with the given number of values and scope 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 values is the number of values to evaluate the engine
  @param scope is the scope of the number of values to evaluate the engine
  @param outputVariables are the output variables to create the surface for
  @throws IOException if any error occurs upon writing the file