docs: function mapChildren(children, func, context) {
    if (children == null) {
      return children;
    }
  
    var mapResult = {};
    var traverseContext = MapBookKeeping.getPooled(mapResult, func, context);
    traverseAllChildren(children, mapSingleChildIntoContext, traverseContext);
    MapBookKeeping.release(traverseContext);
    return ReactFragment.create(mapResult);
  }