code: function renderStatic (
    index,
    isInFor
  ) {
    var tree = this._staticTrees[index];
    // if has already-rendered static tree and not inside v-for,
    // we can reuse the same tree by doing a shallow clone.
    if (tree && !isInFor) {
      return Array.isArray(tree)
        ? cloneVNodes(tree)
        : cloneVNode(tree)
    }
    // otherwise, render a fresh tree.
    tree = this._staticTrees[index] =
      this.$options.staticRenderFns[index].call(this._renderProxy);
    markStatic(tree, ("__static__" + index), false);
    return tree
  }
docs: /* 
  Runtime helper for rendering static trees.