code: function getInstalledNPMVersion () {
    return new Promise((resolve, reject) => {
      let nodeVersion
  
      exec('npm -v', (err, stdout) => {
        if (err) {
          reject(new Error('Could not determine npm version.'))
        } else {
          nodeVersion = stdout.replace(/\n/, '')
          resolve(nodeVersion)
        }
      })
    })
  }
docs: Gets the currently installed version of npm (npm -v)
  @return {Promise.<string>} - Installed version of npm