Task

Display a series of vertical color bars across the width of the display.

The color bars should either use:

   the system palette,   or 
   the sequence of colors: 
   black
   red
   green
   blue
   magenta
   cyan
   yellow
   white


(defun color-bars ()
  (with-screen (scr :input-blocking t :input-echoing nil :cursor-visible nil)
    (dotimes (i (height scr))
      (move scr i 0)
      (dolist (color '(:red :green :yellow :blue :magenta :cyan :white :black))
        (add-char scr #\space :bgcolor color :n (floor (/ (width scr) 8)))))
    (refresh scr)
    ;; wait for keypress
    (get-char scr)))