code: def _after_request(self, response):
          
          # Do not trace if the url is blacklisted
          if utils.disable_tracing_url(flask.request.url, self.blacklist_paths):
              return response
  
          try:
              tracer = execution_context.get_opencensus_tracer()
              tracer.add_attribute_to_current_span(
                  HTTP_STATUS_CODE,
                  str(response.status_code))
          except Exception:  # pragma: NO COVER
              log.error('Failed to trace request', exc_info=True)
          finally:
              return response
docs: A function to be run after each request.
  
          See: http://flask.pocoo.org/docs/0.12/api/#flask.Flask.after_request