code: func NewTimeCollector() (Collector, error) {
  	return &timeCollector{
  		desc: prometheus.NewDesc(
  			namespace+"_time_seconds",
  			"System time in seconds since epoch (1970).",
  			nil, nil,
  		),
  	}, nil
  }
docs: // NewTimeCollector returns a new Collector exposing the current system time in
  // seconds since epoch.