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9.7 Exiting

(exit [v])  any
  v : any/c = #t
Passes v to the current exit handler. If the exit handler does not escape or terminate the thread, #<void> is returned.

(exit-handler)  (any/c . -> . any)
(exit-handler proc)  void?
  proc : (any/c . -> . any)
A parameter that determines the current exit handler. The exit handler is called by exit.

The default exit handler in the Racket executable takes any argument and shuts down the OS-level Racket process. The argument is used as the OS-level exit code if it is an exact integer between 1 and 255 (which normally means “failure”); otherwise, the exit code is 0, (which normally means “success”).