code: public void addEx(double weight, Object xObj, Object yObj, FeatureVector[] fvs) {
          int x = xAlphabet.lookupIndex(xObj);
          int y = yAlphabet.lookupIndex(yObj);
          addEx(weight, x, y, fvs);
      }
docs: Adds a new log-linear model instance.
  
  @param weight The weight of this example.
  @param x The observation, x.
  @param y The prediction, y.
  @param fvs The binary features on the observations, x, for all possible labels, y'. Indexed by y'.