code: public static void d(String msg) {
  		if (!debug) {
  			return;
  		}
  		if (messager == null) {
  			return;
  		}
  		messager.printMessage(Diagnostic.Kind.NOTE, msg);
  	}
docs: Logs debug message.<br>
  No-op if the debugging mode ({@link #debug}) is disabled.
  @param msg Message
  @author vvakame