gistfile1.clj

;the root of the tree.
;each node has a :self key, the value of which is its own value, and a vector
;that contains children.
(def mroot {:self 20 :cren [ 
                            {:self 10 :cren [{:self 11} {:self 12}]} 
                            {:self 30 :cren [{:self 31} {:self 32}]}
                            ]})

;create a zipper from the mroot tree.
(defn mzipper [root]
  (zip/zipper
    #(:cren %) ;branch?
    #(:cren %) ;children
    (fn [node children]
      (with-meta {:self (:self node) :cren (vec children)} (meta node)))
    root))

;only leaf nodes are listed, the parent nodes 20, 10 ,30 are not.    
(is (= '(11 12 31 32) (map :self (map zip/node  (leafnodes (mzipper mroot))))))