public static function setup()
 {
     if (defined(ZIP_MODULE_IMPLEMENTATION_PATH)) {
         $possible_zip_locations = explode(":", ZIP_MODULE_IMPLEMENTATION_PATH);
         //try to find zip executable
         foreach ($possible_zip_locations as $loc) {
             if (is_executable($loc . DIRECTORY_SEPARATOR . "zip")) {
                 self::$zip_exec = $loc . DIRECTORY_SEPARATOR . "zip";
             } else {
                 if (is_executable($loc . DIRECTORY_SEPARATOR . "unzip")) {
                     self::$unzip_exec = $loc . DIRECTORY_SEPARATOR . "unzip";
                 }
             }
         }
     }
 }