private function getBucketIndex($key) {
        /*
         * next, the keys hash is calculated by a
         * private method. Next, the array index
         * (bucket index) is calculated from this hash.
         *
         * Doing this avoids hash collisions.
         */
        $hash = $this->getHash($key);
        $arrayIndex = $this->getArrayIndex($hash);
        return $arrayIndex;
    }