How to use the @angular-devkit/build-angular.executeDevServerBuilder function in @angular-devkit/build-angular

return rxjs_1.from(setup()).pipe(operators_1.switchMap(opt => {
        const webpackTransformFactory = util_1.noneElectronWebpackConfigTransformFactory;
        return build_angular_1.executeDevServerBuilder(opt.buildOptions, context, {
            webpackConfiguration: webpackTransformFactory(opt.buildOptions, opt.buildElectronOptions, context)
        });
    }), operators_1.filter((val, index) => index < 1), operators_1.tap((x) => console.log(x)), operators_1.mapTo({ success: true }));
};

switchMap(opt => {
      const webpackTransformFactory = noneElectronWebpackConfigTransformFactory;

      return executeDevServerBuilder(opt.buildOptions as DevServerBuilderOptions, context, {
        webpackConfiguration: webpackTransformFactory(opt.buildOptions, opt.buildElectronOptions, context)
      });
    }),
    filter((val, index) => index < 1),

export function buildElectronDevServer(options: any, context: BuilderContext): Observable {
  return executeDevServerBuilder(options, context, {
    webpackConfiguration: (config) => {
      return { ...config, target: 'electron-renderer' };
    }
  });
}

switchMap(customWebpackOptions =>
      executeDevServerBuilder(options, context, getTransforms(customWebpackOptions, context))
    )