code: func appender(app storage.Appender, limit int) storage.Appender {
  	app = &timeLimitAppender{
  		Appender: app,
  		maxTime:  timestamp.FromTime(time.Now().Add(maxAheadTime)),
  	}
  
  	// The limit is applied after metrics are potentially dropped via relabeling.
  	if limit > 0 {
  		app = &limitAppender{
  			Appender: app,
  			limit:    limit,
  		}
  	}
  	return app
  }
docs: // appender returns an appender for ingested samples from the target.