Type:	datetime
	ISO-8601 encoded date (e.g 2008-01-01T12:34:00Z)
Name:	finished
	Time task finished (i.e. succeeded or failed). If task-status is pending, then the value of this field has no meaning

Field is read-only

• datetime get_finished (session session_id, task self)

  Get the finished field of the given task.