* bit(i). One pair must differ in output bit(j), and one pair must not. This proves that input
   * bit(i) can alter output bit(j).
   */
  static void checkNoFunnels(HashFunction function) {
    Random rand = new Random(0);
    int keyBits = 32;
    int hashBits = function.bits();

    // output loop tests input bit
    for (int i = 0; i < keyBits; i++) {