The film “Green Book,” starring Mahershala Ali and Viggo Mortensen, is garnering a lot of Oscar buzz. The title is a reference to “The Negro Motorist Green Book,” a travel guide for African Americans that helped them navigate a country that was often hostile towards them. In the movie “Green Book,” classical pianist Dr. Don Shirley is about to embark on a tour in deep south. Knowing the prejudice he’s sure to face, his managers equip his driver, Tony, with the guide.