code: public MultiVariable getAncestorVariable(Class<?> cls) {
  		Variable aux = this;
  		while (!(aux.getClass().equals(cls))) {
  			aux = aux.getParentVariable();
  			if (aux == null) return null;
  		}
  		return (MultiVariable)aux;
  	}
docs: Get the first ancestor {@link MultiVariable} of this {@link Variable} that is of a given type.
  @param cls The type of the ancestor {@link MultiVariable}.
  @return The first ancestor {@link MultiVariable} of this {@link Variable} that is of the given type.