/**
  * Convenience method to merge if the message has a content areas template.
  *
  * @param string $templateBody the template body
  * @param int    $messageId    the message id
  * @param DAO    $dao          an instance of a DAO intended for unit testing
  *
  * @return string|false the generated HTML or false if the message does not have
  *                      a content areas template
  */
 public static function mergeIfTemplate($templateBody, $messageId, DAO $dao = null)
 {
     if (!$templateBody) {
         return false;
     }
     $tm = new self($templateBody);
     if (!$tm->isTemplate()) {
         return false;
     }
     if ($dao === null) {
         $dao = new DAO(new DB());
     }
     $mm = new MessageModel($messageId, $dao);
     return $tm->merge($mm->messageAreas());
 }