code: public String toStringArff() {
  		StringBuilder text = new StringBuilder();
  
  		text.append(ARFF_RELATION).append(" ")
  				.append(Utils.quote(getRelationName())).append("\n\n");
  		for (int i = 0; i < numAttributes(); i++) {
  			text.append(attribute(i).toString()).append("\n");
  		}
  		text.append("\n").append(ARFF_DATA).append("\n");
  
  		text.append(toString());
  		return text.toString();
  
  	}
docs: toString() with header