public function StarRemoveStars($module_id, $item, $date = NULL, $is_draft = NULL)
 {
     // $module_id : string (enum : grn.schedule, grn.mail, grn.message, grn.cabinet, grn.report, grn.bulletin)
     // $item      : item ID (IDType?)
     // $date      : UNIX timestamp (if module_id is 'grn.schedule' set target date)
     // $is_draft  : boolean (if you wish set stars on draft item, set is_draft=true)
     $this->CheckAndSetHeader(__FUNCTION__);
     $reg_args["star_item"]["module_id"] = $module_id;
     $reg_args["star_item"]["item"] = $item;
     if ($date !== NULL) {
         $reg_args["star_item"]["date"] = gmdate(W3C_DATETIME_FORMAT, $date);
     }
     if ($is_draft !== NULL) {
         $reg_args["star_item"]["is_draft"] = $is_draft;
     }
     $this->encodeString($reg_args);
     $results = parent::StarRemoveStars($reg_args);
     $this->methodClose();
     return $this->decodeString($results);
 }