public static function listFolders(Folder $node, $folder_id, $level)
    {
        $px = 15;
        foreach ($node->folders as $folder) {
            ?>
            <div class="folder_in_list" style="margin-left: <?php 
            echo $px;
            ?>
px">
				<img src="<?php 
            echo asset('images/dir.png');
            ?>
" alt="" />
				<?php 
            $style = $folder_id == $folder->folder_id ? 'style="font-weight: bold"' : '';
            echo "<a href=" . URL::to('/id/' . $folder->folder_id) . " " . $style . ">" . $folder->name . "</a>";
            Helpers::listFolders($folder, $folder_id, $level + 1);
            ?>
            </div>
            <?php 
        }
    }