An enum representing the statuses a guest can have for an event.
To call an enum, you call its parent class, name, and property. For example, 
CalendarApp.GuestStatus.INVITED.
Properties
| Property | Type | Description | 
|---|---|---|
| INVITED | Enum | The guest has been invited, but has not indicated whether they are attending. | 
| MAYBE | Enum | The guest has indicated they might attend. | 
| NO | Enum | The guest has indicated they are not attending. | 
| OWNER | Enum | The guest is the owner of the event. | 
| YES | Enum | The guest has indicated they are attending. |