code: function(options, oauth) {
    if (!options) {
      throw new ArgumentError('Missing authenticator options');
    }
  
    if (typeof options !== 'object') {
      throw new ArgumentError('The authenticator options must be an object');
    }
  
    /**
     * Options object for the Rest Client instace.
     *
     * @type {Object}
     */
    var clientOptions = {
      errorFormatter: { message: 'message', name: 'error' }
    };
  
    this.oauth = oauth;
    this.passwordless = new RestClient(options.baseUrl + '/passwordless/start', clientOptions);
    this.clientId = options.clientId;
  }
docs: @class
  Handles authenticator with passwordless flows, e.g. SMS, Touch ID, etc.
  @constructor
  @memberOf module:auth
  
  @param  {Object}              options            Authenticator options.
  @param  {String}              options.baseUrl    The auth0 account URL.
  @param  {String}              [options.clientId] Default client ID.
  @param  {OAuthAuthenticator}  oauth              OAuthAuthenticator instance.