TeePrintStream ts = new TeePrintStream(System.err, "err.log");
TeePrintStream ts = new TeePrintStream(System.err, "err.log", true);
	public static void main(String[] args) throws IOException {		TeePrintStream ts = new TeePrintStream(System.err, "err.log");		System.setErr(ts);		System.err.println("An imitation error message");		ts.close();	}