'Sets feedback to correct hint node in correct map.
Arguments:
student_answers (dict): Dict containing student input.
new_cmap (dict): Dict containing correct map properties.
hint_type (str): Hint type, either `correcthint` or `additional_answer`
hint_index (int): Index of the hint node'

def set_cmap_msg(self, student_answers, new_cmap, hint_type, hint_index):

    hint_nodes = self.xml.xpath(('//numericalresponse[@id=$id]/' + hint_type), id=self.id)
    if hint_nodes:
        hint_node = hint_nodes[hint_index]
        if (hint_type == 'additional_answer'):
            hint_node = hint_nodes[hint_index].find('./correcthint')
        new_cmap[self.answer_id]['msg'] += self.make_hint_div(hint_node, True, [student_answers[self.answer_id]], self.tags[0])
