status = isDoneImpl(obj)
status = isDoneImpl(obj) indicates if an end-of-data condition has occurred. The isDone method should return false when data from a finite source has been exhausted, typically by having read and output all data from the source. You should also define the result of future reads from an exhausted source in the isDoneImpl method.
isDoneImpl is called by the isDone method.
Logical value, true or false, that indicates if an end-of-data condition has occurred or not, respectively.