code: function batchedUpdates(fn, a) {
      var previousIsBatchingUpdates = isBatchingUpdates;
      isBatchingUpdates = true;
      try {
        return fn(a);
      } finally {
        isBatchingUpdates = previousIsBatchingUpdates;
        if (!isBatchingUpdates && !isRendering) {
          performSyncWork();
        }
      }
    }
docs: TODO: Batching should be implemented at the renderer level, not inside the reconciler.