code: public void writeFeatures(PrintWriter fout) throws IOException {
  	// write the number of features
  	fout.println(Integer.toString(features.size()));
  	
  	for (int i = 0; i < features.size(); i++) {
  	    Feature f = (Feature)features.get(i);
  	    fout.println(f.toString(data.cpInt2Str, data.lbInt2Str));
  	}
  	
  	// wirte the line ###...
  	fout.println(Option.modelSeparator);
      }
docs: Write features.
  
  @param fout the fout
  @throws IOException Signals that an I/O exception has occurred.