How to use the @angular/platform-server.PlatformState function in @angular/platform-server

platform.bootstrapModule(prerenderModule.AppModule).then(moduleRef => {
  const state = moduleRef.injector.get(ps.PlatformState);
  const appRef = moduleRef.injector.get(co.ApplicationRef);

  appRef._isStable
    .filter((isStable) => isStable)
    .first()
    .subscribe((stable) => {
      try {
        fs.mkdirSync('./tmp/prerender');
      }
      catch(e){}
      fs.writeFileSync('./tmp/prerender/index.html', state.renderToString(), 'utf-8');
      platform.destroy();
    });
});

([] as any[]),(_l:any) => {
      return i0.ɵmod([i0.ɵmpd(512,i0.ComponentFactoryResolver,i0.ɵCodegenComponentFactoryResolver,
          [[8,([] as any[])],[3,i0.ComponentFactoryResolver],i0.NgModuleRef]),i0.ɵmpd(4608,
          i2.TransferState,i1.ServerTransferState,[i3.PlatformState,i0.RendererFactory2]),
          i0.ɵmpd(512,i1.ServerTransferStateModule,i1.ServerTransferStateModule,([] as any[]))]);
    });
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