/**
  * Create a SimpleUnconstrainedLikelihoodModel instance
  *
  * @param base The base LHCalculator generator to utilise
  * @param model The substitution model
  * @return An appropriate UnconstrianedLikelihoodModel instance
  */
 public static final Instance createInstance(LHCalculator.Factory base, SubstitutionModel model) {
   return new InstanceImpl(
       base.createSeries(model.getNumberOfTransitionCategories(), model.getDataType()), model);
 }
 public String getSubstitutionModelSummary() {
   return model_.toString();
 }