code: def setup(app: Application,
            tracer: Tracer, *,
            skip_routes: Optional[AbstractRoute] = None,
            tracer_key: str = APP_AIOZIPKIN_KEY,
            request_key: str = REQUEST_AIOZIPKIN_KEY) -> Application:
      
      app[tracer_key] = tracer
      m = middleware_maker(skip_routes=skip_routes,
                           tracer_key=tracer_key,
                           request_key=request_key)
      app.middlewares.append(m)
  
      # register cleanup signal to close zipkin transport connections
      async def close_aiozipkin(app: Application) -> None:
          await app[tracer_key].close()
  
      app.on_cleanup.append(close_aiozipkin)
  
      return app
docs: Sets required parameters in aiohttp applications for aiozipkin.
  
      Tracer added into application context and cleaned after application
      shutdown. You can provide custom tracer_key, if default name is not
      suitable.