From https://github.com/MarkEdmondson1234/ga-get-to-post/blob/master/main.py and blogpost http://markedmondson.me/e-mail-open-rate-tracking-with-google-analytics-measurement-protocol-demo

landingpage.py

class LandingPage(webapp2.RequestHandler):
  """Example page where content is - utm parameters should be used plus cid which will link the impression and visit """

  def get(self):

        cid   = cgi.escape(self.request.get('cid'))
        clientId = getUniqueClientId(cid)

        print clientId
      
        template_values = {'clientId' : clientId}

        template = JINJA_ENVIRONMENT.get_template('landing-page.html')
        self.response.write(template.render(template_values))