How to use the angular-in-memory-web-api.InMemoryBackendService function in angular-in-memory-web-api

export function XHRBackendFactory(injector: Injector, browser: BrowserXhr, xsrf: XSRFStrategy, options: ResponseOptions) {
    if (environment.demo) {
        return new InMemoryBackendService(injector, new MockData(), {
            // This is the configuration options
        });
    } else {
        return new XHRBackend(browser, options, xsrf);
    }
}

export function getTestXHRBackend(injector: Injector, browser: BrowserXhr, xsrf: XSRFStrategy, options: ResponseOptions) {
  return new InMemoryBackendService(
    injector,
    new MockApiDataService(),
    {
      passThruUnknownUrl: true,
      rootPath: ''
    }
  );
}