ched strings, to make a palindrome
            def make_palindrome(tokens):
                tokens.extend(reversed([t[::-1] for t in tokens]))
                return ''.join(tokens)
            patt.add_parse_action(make_palindrome)
            print(patt.parse_string("lskdj sdlkjf lksd")) # -> 'lskdjsdlkjflksddsklfjkldsjdksl'
        N)