/**
  * @return array
  */
 public function __sleep()
 {
     return array_merge(parent::__sleep(), ['_privateKey', '_publicKey', '_hostKey']);
 }
 /**
  * @param $umask
  *
  * @return FtpDriver
  */
 public function setUmask($umask)
 {
     parent::setUmask($umask);
     try {
         $this->site('UMASK ' . sprintf('%o', $this->getUmask()));
     } catch (Exception $e) {
     }
     return $this;
 }