public void saveExpression(String fileName, String expression) {
		if (!fileName.contains(".txt")) {
			fileName += ".txt";
		}
		FileWriter writer = null;
		try {
			writer = new FileWriter(fileName);
			PrintWriter fout = new PrintWriter(writer);
			fout.printf(expression,(Object) null);
		} catch (IOException e) {
			System.out.println("ERROR writing files");
		} finally {
			try {
				writer.close();
			} catch (IOException ex) {
				System.out.println("ERROR closing file");
			}
		}
	}