public function set_sheettitle($title) {
        if (!$title) {
            return;
        }

        // Replace any characters in the name that Excel cannot cope with.
        $title = strtr(trim($title, "'"), '[]*/\?:', '       ');
        // Shorten the title if necessary.
        $title = \core_text::substr($title, 0, 31);
        // After the substr, we might now have a single quote on the end.
        $title = trim($title, "'");

        $this->sheettitle = $title;
    }