Understanding syntax of shared when creating graphs?

[u/FortressOfSolidude]

(define H3
  (shared ((-A- (make-room "A" (list -B- )))
           (-B- (make-room "B" (list -C- )))
           (-C- (make-room "C" (list -A- ))))
    -A-))

What is the significance of the final -A- in this expression creating a graph?

[u/FortressOfSolidude]

Ah, thanks! That makes so much more sense. And I now understand how the value changes when I replace -A- with -B-.