/**
  * Return connector instance
  *
  * @return Connector
  */
 public static function &getConnector()
 {
     if (empty(self::$connector)) {
         self::$connector = new Connector();
     }
     return self::$connector;
 }
 public static function setConnector(Connector $connector)
 {
     self::$connector = $connector;
 }