link graphics
procedure main()
   local r
   WOpen("size=400,400","bg=white") | stop("can't open window")
   WAttrib("dx=200","dy=200")
   Fg("light gray")
   every r := 5 to 180 by 2 do DrawCircle(0,0,r,dtor(r),2*dtor(r))
   #WriteImage(&window,"spiral.bmp",-200,-200,400,400)
   WriteImage(&window,"grayspiral.gif",-200,-200,400,400)
   WDone()
end