text: // convert Notification back to value
  
  const { of, Notification } = require('rxjs');
  const { dematerialize, tap } = require('rxjs/operators');
  
  console.log('# dematerialize a stream');
  of(Notification.createNext(0), Notification.createNext(1))
      .pipe(
          tap(x => console.log(x)),
          dematerialize()
      )
      .subscribe(x => console.log(x), e => console.error(e));
  
  // Output
  // Notification { kind: 'N', value: 0, error: undefined, hasValue: true }
  // 0
  // Notification { kind: 'N', value: 1, error: undefined, hasValue: true }
  // 1
  