docs: def close(self):
          """ Close the tunnel.
              If the tunnel is already closed or never opened,
              do nothing.
          """
  
          if self.fd is None:
              return
              
          logger.debug("Closing tunnel '%s'..." % (self.name or "", ))
  
          # Close tun.ko file
          os.close(self.fd)
          self.fd = None
  
          logger.info("Tunnel '%s' closed." % (self.name or "", ))