7 An Example

  (open-graphics)
  ; nothing appears to happen, but the library is initialized...
  
  (define w (open-viewport "practice" 300 300))
  ; viewport window appears
  
  ((draw-line w) (make-posn 30 30) (make-posn 100 100))
  ; line appears
  
  (close-viewport w)
  ; viewport disappears
  
  (close-graphics)
  ; again, nothing appears to happen, but
  ; unclosed viewports (if any) would disappear