code: func UpdateQuota(c context.Context, limit, usage float64, metric, project, region string) {
  	quotaLimit.Set(c, limit, metric, project, region)
  	quotaRemaining.Set(c, limit-usage, metric, project, region)
  	quotaUsage.Set(c, usage, metric, project, region)
  }
docs: // UpdateQuota sets GCE quota metrics.