Depending on the Port connected to the currently leaved Port,
executes the following transition :
Abstractor.Input -> Body (forward)
Abstractor.Body -> Input (backward)
Abstractor.Bind -> Bind (forward -> backward)
Applicator.Input -> Body (forward)
Applicator.Body -> Argument (backward -> forward)
Applicator.Argument -> Input (backward)
Delimitor.Principal -> Auxiliary (forward or backward)
Delimitor.Auxiliary -> Principal (forward or backward)
Duplicator.Input -> Output (forward or backward)
Duplicator.Output -> Input directored by context (forward or backward)
Eraser.Port -> Port (backward -> forward)