(defn annotate [node]
  (cond
    (xml/tag? node)
      (let [node (update-in node [:content] #(map annotate %))] 
        (vary-meta node assoc ::annotations {:emit (tag-emitter node)}))
    (xml/comment? node)
      (vary-meta node assoc ::annotations {:emit (comment-emitter node)})  
    :else node))