How to use the matrix-appservice.AppServiceRegistration function in matrix-appservice

Cli.prototype._generateRegistration = function(appServiceUrl, localpart) {
    if (!appServiceUrl) {
        throw new Error("Missing app service URL");
    }
    var self = this;
    var reg = new AppServiceRegistration(appServiceUrl);
    if (localpart) {
        reg.setSenderLocalpart(localpart);
    }
    this.opts.generateRegistration.bind(this)(reg, function(completeReg) {
        reg = completeReg;
        reg.outputAsYaml(self.opts.registrationPath);
        console.log("Output registration to: " + self.opts.registrationPath);
        process.exit(0);
    });
};

generateRegistration: function(appServiceUrl, callback) {
        var reg = new AppServiceRegistration(appServiceUrl);
        reg.setHomeserverToken(AppServiceRegistration.generateToken());
        reg.setAppServiceToken(AppServiceRegistration.generateToken());
        reg.setSenderLocalpart("vertobot");
        reg.addRegexPattern("users", "@" + USER_PREFIX + ".*", true);
        console.log(
            "Generating registration to '%s' for the AS accessible from: %s",
            REGISTRATION_FILE, appServiceUrl
        );
        callback(reg);
    },
    run: runBridge

generateRegistration: function(callback) {
        var reg = new AppServiceRegistration("http://localhost:8008");
        reg.setHomeserverToken(AppServiceRegistration.generateToken());
        reg.setAppServiceToken(AppServiceRegistration.generateToken());
        reg.setSenderLocalpart("bridge-example");
        reg.addRegexPattern("users", "@example_.*", true);
        console.log("Generating registration to 'my-bridge-registration.yaml'");
        callback(reg);
    }
});