docs: public static long safeSubtract(long val1, long val2) {
          long diff = val1 - val2;
          // If there is a sign change, but the two values have different signs...
          if ((val1 ^ diff) < 0 && (val1 ^ val2) < 0) {
              throw new ArithmeticException
                  ("The calculation caused an overflow: " + val1 + " - " + val2);
          }
          return diff;
      }