code: def health(self, request):
          
          if self.health_handler is None:
              return self._no_health_handler(request)
  
          health = self.health_handler()
          response_code = OK if health.healthy else SERVICE_UNAVAILABLE
          request.setResponseCode(response_code)
          write_request_json(request, health.json_message)
docs: Listens to incoming health checks from Marathon on ``/health``.