code: function HerokuAddonStrategy(options) {
  
    if (!options || !options.sso_salt) throw new Error('Passport Heroku Addon strategy requires a sso_salt');
  
    passport.Strategy.call(this);
    this.name = 'heroku-addon';
    this._sso_salt = options.sso_salt;
    this._passReqToCallback = options.passReqToCallback;
  }
docs: `HerokuAddonStrategy` constructor.
  
  The Heroku Addon authentication strategy authenticates requests based on
  request id and timestamp parameters.
  
  Applications must supply a `sso_salt` secret to validate requests.
  
  Examples:
  
  passport.use(new HerokuAddonStrategy({
  sso_salt: 'secret'
  }));
  
  @param {Object} options
  @api public