code: func NewNetClassCollector() (Collector, error) {
  	fs, err := sysfs.NewFS(*sysPath)
  	if err != nil {
  		return nil, fmt.Errorf("failed to open sysfs: %v", err)
  	}
  	pattern := regexp.MustCompile(*netclassIgnoredDevices)
  	return &netClassCollector{
  		fs:                    fs,
  		subsystem:             "network",
  		ignoredDevicesPattern: pattern,
  		metricDescs:           map[string]*prometheus.Desc{},
  	}, nil
  }
docs: // NewNetClassCollector returns a new Collector exposing network class stats.