code: def get_line_configuration_message(self, line_number):
          
          if line_number not in self._line_configuration_message_cache:
              line_bytes = self.get_bytes(line_number)
              if line_bytes is not None:
                  line_bytes = bytes([line_number & 255]) + line_bytes
                  line_bytes += bytes([self.is_last(line_number)])
                  line_bytes += crc8(line_bytes).digest()
              self._line_configuration_message_cache[line_number] = line_bytes
              del line_bytes
          line = self._line_configuration_message_cache[line_number]
          if line is None:
              # no need to cache a lot of empty lines
              line = (bytes([line_number & 255]) +
                      b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' +
                      b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01')
              line += crc8(line).digest()
          return line
docs: Return the cnfLine content without id for the line.
  
          :param int line_number: the number of the line
          :rtype: bytes
          :return: a cnfLine message without id as defined in :ref:`cnfLine`