{$reference SmallBasicLibrary.dll}
uses Microsoft.SmallBasic.Library,System;
type gw = GraphicsWindow;
type t = turtle;
var n := 0;
procedure OnTick();
begin
  if n mod 2 = 0 then t.Hide
    else t.Show;
  n += 1;   
end;
begin
  gw.Width := 640;
  gw.Height := 520;
  // код пишем сюда
  Timer.Interval := 250;
  Timer.Pause;
  Timer.Tick += OnTick;
  Timer.Resume;
  
end.