text: def main(request, response):
      """
      Check that headers sent to navigate here *do* contain the device-memory client
      hint, and report success/failure in a way compatible with
      verify_{subresource|iframe}_state() in accept-ch-test.js
      """
  
      if b"device-memory" in request.headers and b"sec-ch-device-memory" in request.headers:
        result = u"PASS"
      else:
        result = u"FAIL"
  
      content = u'''
  <script>
    let messagee = window.opener || window.parent;
    messagee.postMessage("%s" , "*");
  </script>
  ''' % (result)
      headers = [(b"Content-Type", b"text/html"), (b"Access-Control-Allow-Origin", b"*")]
      return 200, headers, content
  