if (Character.isLetter (c)) { c = (Character.isUpperCase (c) ? Character.toLowerCase (c) : Character.toUpperCase (c)); }
                    public void work ()                    {                        char c = input.popChar ();                        if (Character.isLetter (c))                        {                            c = (Character.isUpperCase (c) ? Character.toLowerCase (c) : Character.toUpperCase (c));                        }                        output.pushChar (c);                    }