code: public static String styleClasses(Collection<? extends BaseStyler> l) {
        if (l == null) {
           return "argument is null";
        }
  
        for (BaseStyler st : l) {
           if (st instanceof DebugStyler) {
              return ((DebugStyler) st).getStyleSetup().toString();
           }
        }
  
        return "";
     }
docs: for debugging, uses {@link DebugStyler#getStyleSetup() } to return classNames
  
  @param l
  @return