code: function outputVersion () {
    fs.readFile(path.join(__dirname, '/../package.json'), function (err, data) {
      if (err) {
        console.log(err.toString())
      } else {
        const pkg = JSON.parse(data)
        const version = pkg && pkg.version ? pkg.version : 'unknown'
        console.log(version)
      }
      process.exit(0)
    })
  }
docs: Output application version number.
  Version number is read version from package.json.