private String updateBasedOnPop(){
        String pop = (String)navigationStack.pop();
        if(pop.equals("person")){
            if(!personStack.isEmpty()){
                updatePersonCard((Person)personStack.pop());
            }           
        } else if(pop.equals("movie")){
            if(!movieStack.isEmpty()){
                updateMovieCard((Movie)movieStack.pop());
            }           
        }
        return pop;
    }