func namespacedTree(tree *parse.Tree, ns []string) *parse.Tree {
tree = tree.Copy()
if len(ns) > 0 {
prefix := strings.Join(ns, nsSep) + nsMark
templateutil.WalkTree(tree, func(n, p parse.Node) {
if n.Type() == parse.NodeTemplate {
tmpl := n.(*parse.TemplateNode)
tmpl.Name = prefix + tmpl.Name
}
})
}
return tree
}
