set req.http.X-Fastly-Imageopto-Api = "fastly";
if(req.url == "/") {
  set req.http.x-fastly-imageopto-montage =
"width=500&height=250&layout=2b&crop=smart&images=/fastly-fiddle-examples/images/obama2.jpg;/fastly-fiddle-examples/images/obama.jpg";
}