procedure main()
WOpen("size=800,600", "bg=black", "fg=white") | stop("*** cannot open window")
drawtree(400,500,-90,9)
WDone()
end

link WOpen

procedure drawtree(x,y,angle,depth)
if depth > 0 then {
   x2 := integer(x + cos(dtor(angle)) * depth * 10)
   y2 := integer(y + sin(dtor(angle)) * depth * 10)
   DrawLine(x,y,x2,y2)
   drawtree(x2,y2,angle-20, depth-1)
   drawtree(x2,y2,angle+20, depth-1)
   }
return
end