--------

(defn get-in*
  "Returns the value in a nested associative structure,
  where ks is a sequence of keys. Returns nil if the key is not present,
  or the not-found value if supplied."
  {:added "1.2"
   :static true}
  ([m ks]
     (reduce get m ks))
  ([m ks not-found]
     (loop [sentinel lookup-sentinel
            m m
            ks (seq ks)]
       (if ks
         (if-not (satisfies? ILookup m)
           not-found
           (let [m (get m (first ks) sentinel)]
             (if (identical? sentinel m)
               not-found
               (recur sentinel m (next ks)))))
         m))))