protected function delete_files($questionid, $contextid) {
$fs = get_file_storage();
parent::delete_files($questionid, $contextid);
$this->delete_files_in_answers($questionid, $contextid, true);
$this->delete_files_in_hints($questionid, $contextid);
$fs->delete_area_files($contextid, 'qtype_calculatedmulti',
'correctfeedback', $questionid);
$fs->delete_area_files($contextid, 'qtype_calculatedmulti',
'partiallycorrectfeedback', $questionid);
$fs->delete_area_files($contextid, 'qtype_calculatedmulti',
'incorrectfeedback', $questionid);
}
