* and increasing the threshold to 2^32 doesn't pay for itself, and adding another enum
         * constant hurts performance further -- I suspect because bimorphic implementation is a
         * sweet spot for the JVM.
         */
        return (a * b) % m;
      }

      @Override
      long squareMod(long a, long m) {
        return (a * a) % m;
      }
    },