info.setSystemId(getSystemId());
info.setProperty("label", label);
info.setProperty("value", val);
TraceListener listener = context.getController().getTraceListener();
listener.enter(info, context);
listener.leave(info);
}
private void traceItem(Item val, String label, PrintStream out) {
if (val==null) {
out.println(label + ": empty sequence");