code: func init() {
  	for _, arg := range os.Args {
  		flag := strings.TrimLeft(arg, "-")
  
  		for _, enabler := range enablerFlags {
  			if !Enabled && flag == enabler {
  				log.Info("Enabling metrics collection")
  				Enabled = true
  			}
  		}
  		for _, enabler := range expensiveEnablerFlags {
  			if !EnabledExpensive && flag == enabler {
  				log.Info("Enabling expensive metrics collection")
  				EnabledExpensive = true
  			}
  		}
  	}
  }
docs: // Init enables or disables the metrics system. Since we need this to run before
  // any other code gets to create meters and timers, we'll actually do an ugly hack
  // and peek into the command line args for the metrics flag.