code: public double distance(Synset synset1, Synset synset2) {
          Preconditions.checkNotNull(synset1);
          Preconditions.checkNotNull(synset2);
          if (synset1.equals(synset2)) {
              return 0d;
          }
          List<Synset> path = shortestPath(synset1, synset2);
          return path.isEmpty() ? Double.POSITIVE_INFINITY : path.size() - 1;
      }
docs: Calculates the distance between synsets.
  
  @param synset1 Synset 1
  @param synset2 Synset 2
  @return The distance