How to use the librato-node.on function in librato-node

const clusterWorkerSize = parseInt(process.env.CLUSTER_WORKERS, 10) || 1
const simultaneousWorkerRenders = parseInt(process.env.SIMULTANEOUS_RENDERS, 10) || 1
const renderProcessTimeout = parseInt(process.env.RENDER_PROCESS_TIMEOUT, 10) || 60
const renderJobTtl = (parseInt(process.env.RENDER_JOB_TTL, 10) || 30) * 1000

// Periodically clear stuck jobs
queue.watchStuckJobs()

// Report Kue stats to Librato
librato.configure({
  email: process.env.LIBRATO_EMAIL,
  token: process.env.LIBRATO_TOKEN,
  source: process.env.DYNO,
})
librato.start()
librato.on('error', (err) => {
  Honeybadger.notify(err)
  console.error(err)
})

const libratoReporter = setInterval(() => {
  queue.inactiveCount((err, total) => {
    if (!err) {
      librato.measure('kue.inactive.count', total)
    }
  })
  queue.activeCount((err, total) => {
    if (!err) {
      librato.measure('kue.active.count', total)
    }
  })
  queue.failedCount((err, total) => {

return data
}))

// Parse cookies (for determining to pre-render or not)
app.use(cookieParser())

// Send stats to Librato
librato.configure({
  email: process.env.LIBRATO_EMAIL,
  token: process.env.LIBRATO_TOKEN,
  source: process.env.DYNO,
})
librato.start()
app.use(librato.middleware())

librato.on('error', (err) => {
  console.log('[librato] ERROR', err)
})

// Use Helmet to lock things down
app.use(helmet())

const indexStr = fs.readFileSync(path.join(__dirname, './../../public/index.html'), 'utf-8')
const stats = JSON.parse(fs.readFileSync(path.join(__dirname, './../../webpack-stats/server.json'), 'utf-8'))

// Wire up OAuth route
addOauthRoute(app)

// Assets
app.use(express.static('public', { index: false, redirect: false }))
app.use('/static', express.static('public/static', { maxAge: '1y', index: false, redirect: false, fallthrough: false }))