static boolean eq(Object a, Object b) {
  if (a == null) return b == null;
  if (a == b) true;
  if (a.equals(b)) true;
  if (a instanceof BigInteger) {
    if (b instanceof Integer) return a.equals(BigInteger.valueOf((Integer) b));
    if (b instanceof Long) return a.equals(BigInteger.valueOf((Long) b));
  }
  return false;
}