code: private void setModelContext(InstancesHeader ih){
  		//TODO possibly refactored
          if ((ih != null) && (ih.classIndex() < 0)) {
              throw new IllegalArgumentException(
                      "Context for a classifier must include a class to learn");
          }
          //TODO: check flag for checking whether training has started or not
          
          //model context is used to describe the model
  		logger.trace("Model context: {}", ih.toString());
  	}
docs: Helper method to set the model context, i.e. how many attributes they are and what is the class index
  @param ih