(let [old-grid     (:grid world)
        f1           (fn [k] (:grid-coord (get old-grid k)))
        f            (fn [k] (not (= k (:grid-coord (get old-grid k)))))
        d            (let [mismatch-keys (doall (filter f (keys old-grid)))]
                       (if (> (count mismatch-keys) 0)
                         (let [grc (doall (map f1 (keys old-grid)))]
                           (throw (Exception. (str "key mismatch! " (vec mismatch-keys) " GRC: " (vec grc)))))))