title: Prevent hot linking for get_serving_url() in Google App Engine
body: <p>Is there a way to prevent hot linking for images that are served by the Images Service method get_serving_url()?</p>
  
  <p>I only found <a href="https://stackoverflow.com/q/903144/734765">this answer</a> but I don't think it would apply to get_serving_url().</p>