function __construct($steam_object = FALSE)
 {
     self::$PATH = PATH_EXTENSIONS . "units_elearning/";
     self::$DISPLAY_NAME = gettext("elearning course material");
     self::$DISPLAY_DESCRIPTION = gettext("Here you can add elearning material");
     parent::__construct(PATH_EXTENSIONS . "units_elearning.xml", $steam_object);
     if (!defined("PATH_TEMPLATES_UNITS_ELEARNING")) {
         define("PATH_TEMPLATES_UNITS_ELEARNING", PATH_EXTENSIONS . "units_elearning/templates/");
     }
     $this->cache = get_cache_function("unit_elearning", 3600);
 }