Section - Going Back
The former location is a room that varies.
First carry out going rule (this is the update the former location rule):
change the former location to the location.
Understand "go back" as retreating. Understand "back" or "return" or "retreat" as retreating.
Retreating is an action applying to nothing.
Check retreating when the former location is the location: say "You haven't gone anywhere yet." instead.
Carry out retreating:
if former location is an adjacent room, head to former location;
otherwise say "You can't see an open way back."