code: public static void warn(String message) {
          if (Boolean.getBoolean("visibleassertions.silence")) {
              return;
          }
  
          System.out.println("        " + yellow(bright(WARN_MARK + " " + message)));
      }
docs: Log a warning message.
  <p>
  The output will be in yellow, following a '!' symbol.
  
  @param message message to output