(defn stack-hash
    "Creates a hash of in which fits in size with minimal rehashing given various sizes. Optional n argument can be specified if it has been precomputed"
    [in size]
    (let [n (Math/ceil (/ (Math/log size) (Math/log 2)))
          Hv (loop [i 0
                h 0]
                (if (> (count in) i)
                    (recur  (+ i 1)
                        (mod (+ (* h 31) (int (.charAt in i))) Integer/MAX_VALUE))
                h))
          mask (int (- (Math/pow 2 n) 1))
          first-four (bit-and Hv mask)]
        (if (<= first-four size)
            first-four
            (stack-hash (str first-four)))
    ))