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