This method will flag a reservation as checked in.
|rez_id||Integer||This is the unique identifier of the reservation we want to flag as checked-in.|
|business_code||Integer||(Optional) Business Code of the business we are retrieving theme data for. If neither business_id or business_code are specified, the user's session is used to select business.|
|format||enumeration||(optional) Set this value to "xml" for XML raw formatted output, "xml-clean" for XML tidy formatted output or "json" for JSON formatted output. If not passed, "xml" is used as a default|