docs: function Credentials (options) {
    EventEmitter.call(this)
  
    options.keys.apiVersion = 'latest'
    options.keys.sslEnabled = true
  
    if (options.hasOwnProperty('upgrade')) {
      // Update with the MFA token passed in with the credentials
      this.upgrade(options)
      return
    }
  
    let awsConfig = Object.assign({}, options.keys)
  
    // Else not using a MFA token
    this._awsConfig = new AWS.Config(awsConfig)
  
    // Upgrade creditials not necessary. Tell the caller ready.
    internals.emitAsync.call(this, internals.EVENT_INITIALIZED, null, { state: 'ok' })
  }