anchor.diff:  (define (display-access-points)
     (! "nmcli device wifi list"))
   
  -(define (join-access-point cmd-args)
  +(define (join-access-point cmd-args script)
     (if (= cmd-args '())
  -    (begin
  -      (display-missing-subcmd "join")
  -      (usage script)))
  +     (display-missing-subarg "join" script))
     (let ((ssid (first cmd-args))
           (cmd-args (rest cmd-args)))
       (println (format "Connecting to SSID %s ..." ssid))
  
positive.code:   (println (format "\nERROR: Unknown command '%s'." cmd))
    (usage script))
  
  (define (display-missing-subcmd cmd subcmd script)
    (println (format "\nERROR: Command '%s' is missing required subcommand."
                     cmd)))
  
  (define (display-unknown-subcmd cmd subcmd script)
    (println (format "\nERROR: Unknown subcommand '%s' for command '%s'."
                     subcmd cmd)))
  
  ;;;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
  ;;; Supporting functions
  
negative.code:         (cmd-args (rest opts)))
      (case cmd
        ("scan" (display-access-points))
        ("join" (join-access-point cmd-args script))
        (true (display-unknown-cmd cmd script))))
    (exit))
  
  