docs: def _convert_netmask(mask):
      """Convert netmask from CIDR format(integer) to doted decimal string."""
      if mask not in range(0, 33):
          raise scci.SCCIInvalidInputError(
              'Netmask value is invalid.')
  
      return socket.inet_ntoa(struct.pack(
          '!L', int('1' * mask + '0' * (32 - mask), 2)))