/**
  * Clears static properties after reaching the end of parsing.
  *
  * This is to prevent any lingering properties when used in a loop.
  */
 protected static function clear_properties()
 {
     self::$headers = array();
     self::$querystring = '';
     self::$user = false;
     self::$content = '';
     self::$subject = '';
     self::$is_html = false;
 }