export function mapVNode<A, B>(f: (_: A) => B, v: VNode<A>): VNode<B> {
  let data = v.data || {};
  if (isThunk(v)) {
    const ndata = T.assign({}, v.data, {
      cofn: T.o(f, data.cofn as any)
    }) as VNodeData<B>;
    return T.set('data', ndata, v as any);
  }
  if (typeof data.cofn === 'function') {
    return V.vnode(v.sel,
      T.assign({}, data as any, {
        cofn: T.o(f, data.cofn),
        hook: {
          init: initMapHook,
          prepatch: prepatchMapHook
        }
      }),
      v.children, v.text, v.elm as Element);
  }
  return V.vnode(v.sel,
    T.assign({}, data as any, {
      cofn: f,
      hook: {
        init: initMapHook,
        prepatch: prepatchMapHook
      }
    }),
    v.children, v.text, v.elm as Element);
}

 node =>
   node
     ? vnode(
         node.sel + scope,
         node.data,
         node.children,
         node.text,
         node.elm as any,
       )
     : node,

 private wrapDocFrag(children: Array<VNode>) {
   return vnodeFn('', {}, children, undefined, this.rootElement as any);
 }

 return sink.map((node: VNode) =>
   vnode(node.sel + scope, node.data, node.children, node.text, node.elm as any),