def extend( self, itemseq ):
        """
        Add sequence of elements to end of ParseResults list of elements.

        Example::

            patt = OneOrMore(Word(alphas))

            # use a parse action to append the reverse of the matched strings, to make a palindrome
            def make_palindrome(tokens):
                tokens.extend(reversed([t[::-1] for t in tokens]))
                return ''.join(tokens)
            print(patt.addParseAction(make_palindrome).parseString("lskdj sdlkjf lksd")) # -> 'lskdjsdlkjflksddsklfjkldsjdksl'
        """
        if isinstance(itemseq, ParseResults):
            self += itemseq
        else:
            self.__toklist.extend(itemseq)