How to use the @firebase/util.deepExtend function in @firebase/util

if (appArg === void 0) { appArg = app(); }
            // @ts-ignore
            if (typeof appArg[name] !== 'function') {
                // Invalid argument.
                // This happens in the following case: firebase.storage('gs:/')
                throw ERROR_FACTORY.create("invalid-app-argument" /* INVALID_APP_ARGUMENT */, {
                    appName: name
                });
            }
            // Forward service instance lookup to the FirebaseApp.
            // @ts-ignore
            return appArg[name]();
        }
        // ... and a container for service-level properties.
        if (serviceProperties !== undefined) {
            util.deepExtend(serviceNamespace, serviceProperties);
        }
        // Monkey-patch the serviceNamespace onto the firebase namespace
        // @ts-ignore
        namespace[name] = serviceNamespace;
        // Patch the FirebaseAppImpl prototype
        // @ts-ignore
        firebaseAppImpl.prototype[name] =
            // TODO: The eslint disable can be removed and the 'ignoreRestArgs'
            // option added to the no-explicit-any rule when ESlint releases it.
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            function () {
                var args = [];
                for (var _i = 0; _i < arguments.length; _i++) {
                    args[_i] = arguments[_i];
                }
                var serviceFxn = this._getService.bind(this, name);

if (appArg === void 0) { appArg = app(); }
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                if (typeof appArg[componentName] !== 'function') {
                    // Invalid argument.
                    // This happens in the following case: firebase.storage('gs:/')
                    throw ERROR_FACTORY.create("invalid-app-argument" /* INVALID_APP_ARGUMENT */, {
                        appName: componentName
                    });
                }
                // Forward service instance lookup to the FirebaseApp.
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                return appArg[componentName]();
            };
            // ... and a container for service-level properties.
            if (component.serviceProps !== undefined) {
                util.deepExtend(serviceNamespace, component.serviceProps);
            }
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            namespace[componentName] = serviceNamespace;
            // Patch the FirebaseAppImpl prototype
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            firebaseAppImpl.prototype[componentName] =
                // TODO: The eslint disable can be removed and the 'ignoreRestArgs'
                // option added to the no-explicit-any rule when ESlint releases it.
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                function () {
                    var args = [];
                    for (var _i = 0; _i < arguments.length; _i++) {
                        args[_i] = arguments[_i];
                    }
                    var serviceFxn = this._getService.bind(this, componentName);
                    return serviceFxn.apply(this, component.multipleInstances ? args : []);

if (appArg === void 0) { appArg = app(); }
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                if (typeof appArg[componentName] !== 'function') {
                    // Invalid argument.
                    // This happens in the following case: firebase.storage('gs:/')
                    throw ERROR_FACTORY.create("invalid-app-argument" /* INVALID_APP_ARGUMENT */, {
                        appName: componentName
                    });
                }
                // Forward service instance lookup to the FirebaseApp.
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                return appArg[componentName]();
            };
            // ... and a container for service-level properties.
            if (component.serviceProps !== undefined) {
                deepExtend(serviceNamespace, component.serviceProps);
            }
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            namespace[componentName] = serviceNamespace;
            // Patch the FirebaseAppImpl prototype
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            firebaseAppImpl.prototype[componentName] =
                // TODO: The eslint disable can be removed and the 'ignoreRestArgs'
                // option added to the no-explicit-any rule when ESlint releases it.
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                function () {
                    var args = [];
                    for (var _i = 0; _i < arguments.length; _i++) {
                        args[_i] = arguments[_i];
                    }
                    var serviceFxn = this._getService.bind(this, componentName);
                    return serviceFxn.apply(this, component.multipleInstances ? args : []);

function serviceNamespace(appArg = app()) {
            // @ts-ignore
            if (typeof appArg[name] !== 'function') {
                // Invalid argument.
                // This happens in the following case: firebase.storage('gs:/')
                throw ERROR_FACTORY.create("invalid-app-argument" /* INVALID_APP_ARGUMENT */, {
                    appName: name
                });
            }
            // Forward service instance lookup to the FirebaseApp.
            // @ts-ignore
            return appArg[name]();
        }
        // ... and a container for service-level properties.
        if (serviceProperties !== undefined) {
            deepExtend(serviceNamespace, serviceProperties);
        }
        // Monkey-patch the serviceNamespace onto the firebase namespace
        // @ts-ignore
        namespace[name] = serviceNamespace;
        // Patch the FirebaseAppImpl prototype
        // @ts-ignore
        firebaseAppImpl.prototype[name] =
            // TODO: The eslint disable can be removed and the 'ignoreRestArgs'
            // option added to the no-explicit-any rule when ESlint releases it.
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            function (...args) {
                const serviceFxn = this._getService.bind(this, name);
                return serviceFxn.apply(this, allowMultipleInstances ? args : []);
            };
        return serviceNamespace;
    }

extendApp(props) {
        // Copy the object onto the FirebaseAppImpl prototype
        deepExtend(this, props);
    }
    /**

function extendNamespace(props) {
        deepExtend(namespace, props);
    }
    return namespace;

function extendNamespace(props) {
        util.deepExtend(namespace, props);
    }
    return namespace;

function extendNamespace(props: { [prop: string]: unknown }): void {
    deepExtend(namespace, props);
  }