Fires whenever a control segment is read that marks the end of an interchange.
The 'callback' is called when the 'EndFunctionalGroup' event is emited.
The argument 'e' has the following properties:
e.tag e.controlNumber e.count e.fullSegment
The EndFunctionalGroup event will fire when a control segment marking the end of a functional group is read. The Tag parameter contains the tag of the segment, such as GE. ControlNumber contains the control number associated with the segment, and links this event with the corresponding StartFunctionalGroup event. Count contains the value of the count element included in the closing segment, which identifies the number of transactions in a functional group.