+ #:to 'playroom)
+ (make <exit>
+ #:name "down"
+ #:to 'underground-lab
+ #:traverse-check
+ (lambda (exit room whos-exiting)
+ (define panel-open
+ (mbody-val (<-wait (dyn-ref room 'computer-room:floor-panel)
+ 'open?)))
+ (if panel-open
+ (values #t "You descend the spiral staircase.")
+ (values #f '("You'd love to go down, but the only way "
+ "through is through that metal panel, "
+ "which seems closed.")))))))