/**
  * cleans command(s) of transfer
  *
  * @param $transfer
  * @return boolean
  */
 function clean($transfer)
 {
     global $instanceCommandHandler;
     // initialize if needed
     if (!isset($instanceCommandHandler)) {
         CommandHandler::initialize();
     }
     // call instance-method
     return $instanceCommandHandler->instance_clean($transfer);
 }