@Override
 public double computeRelativeFrequency(int k) {
   return (double) counts.get(k) / getSumOfCounts();
 }
 @Override
 public double computeLogRelativeFrequency(int k) {
   return Math.log(counts.get(k)) - Math.log(getSumOfCounts());
 }
 @Override
 public int get(int key) {
   return counts.get(key);
 }