public function proxy( string $address, int $port = 1080, $type = \CURLPROXY_HTTP, bool $tunnel = false )
      : Request
   {

      $this->_proxy[ 'type' ]    = $type;
      $this->_proxy[ 'port' ]    = $port;
      $this->_proxy[ 'tunnel' ]  = $tunnel;
      $this->_proxy[ 'address' ] = $address;

      return $this;

   }