Node JS Simple Singleton used by require()

singleton.js

var singleton = function () {
  // all are public
  var someVariable = "some value"   // acts like states
  var otherVariable = 123           // acts like states
  
  return {
    someFunction: function (someArg) {
      // expressions go here, change state
      return "other value"
    },
    otherFunction: function () {
      var someValue = this.someFunction()   // must call with this to get into the context
      otherVariable = (someValue + someVariable).length // for the variables, let the closures rock you!
    }
  }
}()   // *** this is important

module.exports = singleton