text: import os.path
  import zope.app.appsetup.product
  
  
  class HealthCheck:
  
      def __call__(self):
          config = zope.app.appsetup.product.getProductConfiguration('zeit.cms')
          stopfile = config.get('stopfile')
          if stopfile and os.path.exists(stopfile):
              self.request.response.setStatus(500)
              return 'fail: stopfile %s present' % stopfile
          return 'OK'
  