def _hm_form_message_crc(<EOL>self,<EOL>thermostat_id,<EOL>protocol,<EOL>source,<EOL>function,<EOL>start,<EOL>payload<EOL>):
data = self._hm_form_message(<EOL>thermostat_id, protocol, source, function, start, payload)<EOL>crc = CRC16()<EOL>data = data + crc.run(data)<EOL>return data<EOL>
Forms a message payload, including CRC