'Extract numericalresponse extended hint, e.g.
<correcthint>Yes, 1+1 IS 2<correcthint>'

def get_extended_hints(self, student_answers, new_cmap):

    if (self.answer_id in student_answers):
        if (new_cmap.cmap[self.answer_id]['correctness'] == 'correct'):
            if (self.additional_answer_index == (-1)):
                self.set_cmap_msg(student_answers, new_cmap, 'correcthint', 0)
            else:
                self.set_cmap_msg(student_answers, new_cmap, 'additional_answer', self.additional_answer_index)
