Use this method to set the event's ID. If not set, an UID will be generated randomly. When output, the ID will be suffixed with '@' + your calendar's domain.
#### sequence([_Number_ sequence])
Use this method to set the event's revision sequence number of the
calendar component within a sequence of revisions.
#### start([_Date_ start])
Appointment date of beginning as Date object. This is required for all events!