const cbStore = require('callback-store')

let callbacks = cbStore()
let uid = Math.random()
callbacks.add(uid, function(err) {
  if (err) {
    /* An error will happen if the callback isn't executed during 5 seconds */
    return
  }
  console.log('Hello world!')
}, 5000)

/* ... */

let cb = callbacks.get(uid)
cb()