code: def cancel_port_forward(self, address, port):
          
          if not self.active:
              return
          self._tcp_handler = None
          self.global_request("cancel-tcpip-forward", (address, port), wait=True)
docs: Ask the server to cancel a previous port-forwarding request.  No more
          connections to the given address & port will be forwarded across this
          ssh connection.
  
          :param str address: the address to stop forwarding
          :param int port: the port to stop forwarding