/**
     * Internal function - creates htmls structure suitable for YUI tree.
     *
     * @param assign_files $tree
     * @param array $dir
     * @return string
     */
    protected function htmllize_tree(assign_files $tree, $dir) {
        global $CFG;
        $yuiconfig = array();
        $yuiconfig['type'] = 'html';

        if (empty($dir['subdirs']) and empty($dir['files'])) {
            return '';
        }

        $result = '<ul>';
        foreach ($dir['subdirs'] as $subdir) {
            $image = $this->output->pix_icon(file_folder_icon(),
                                             $subdir['dirname'],
                                             'moodle',
                                             array('class'=>'icon'));
            $result .= '<li yuiConfig=\'' . json_encode($yuiconfig) . '\'>' .
                       '<div>' . $image . ' ' . s($subdir['dirname']) . '</div> ' .
                       $this->htmllize_tree($tree, $subdir) .
                       '</li>';
        }

        foreach ($dir['files'] as $file) {
            $filename = $file->get_filename();
            if ($CFG->enableplagiarism) {
                require_once($CFG->libdir.'/plagiarismlib.php');
                $plagiarismlinks = plagiarism_get_links(array('userid'=>$file->get_userid(),
                                                             'file'=>$file,
                                                             'cmid'=>$tree->cm->id,
                                                             'course'=>$tree->course));
            } else {
                $plagiarismlinks = '';
            }
            $image = $this->output->pix_icon(file_file_icon($file),
                                             $filename,
                                             'moodle',
                                             array('class'=>'icon'));
            $result .= '<li yuiConfig=\'' . json_encode($yuiconfig) . '\'>' .
                           '<div>' . $image . ' ' .
                                     $file->fileurl . ' ' .
                                     $plagiarismlinks . ' ' .
                                     $file->portfoliobutton . ' ' .
                                     // Added
                                     // Start
                                     $file->createdAt .
                                     // End
                            '</div>' .
                       '</li>';
        }

        $result .= '</ul>';

        return $result;
    }