How to use the @angular/service-worker.ServiceWorkerPlugin function in @angular/service-worker

mangle: false
      });

      // Required here since the package isn't installed for non-mobile apps.
      var ServiceWorkerPlugin = require('@angular/service-worker').ServiceWorkerPlugin;
      // worker.js is needed so it can be copied to dist
      var workerJsTree = new BroccoliFunnel(jsTree, {
        include: ['vendor/@angular/service-worker/dist/worker.js']
      });
      /**
       * ServiceWorkerPlugin will automatically pre-fetch and cache every file
       * in the tree it receives, so it should only receive the app bundle,
       * and non-JS static files from the app. The plugin also needs to have
       * the worker.js file available so it can copy it to dist.
       **/
      var swTree = new ServiceWorkerPlugin(BroccoliMergeTrees([
        bundleTree,
        assetsTree,
        workerJsTree
      ]));
      bundleTree = BroccoliMergeTrees([bundleTree, swTree], {
        overwrite: true
      });
    }

    return BroccoliMergeTrees([nonJsTree, scriptTree, bundleTree], { overwrite: true });
  }
}