@Override
 public DiscreteCountBipolarSentiment add(Integer s) {
   DiscreteCountBipolarSentiment c = this.clone();
   return c.addInplace(s);
 }
 @Override
 public DiscreteCountBipolarSentiment subtractInplace(DiscreteCountBipolarSentiment s) {
   return this.addInplace(s.multiply(-1));
 }