docs: def _get_default_gateway(self, ip=4):
          """
          Returns the default gateway for given IP version. The ``ip`` argument
          is used to specify the IP version, and can be either 4 or 6.
          """
          net_type = netifaces.AF_INET if ip == 4 else netifaces.AF_INET6
          gw = netifaces.gateways()['default'].get(net_type, (None, None))
          if gw[1] == self.name:
              return gw[0]