Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
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Question: The film Schindler's List was based on whose Booker Prize winning novel of 1982?

Answer: schindler's list


Question: Who played Lionel Hardcastle in the TV series 'As Time Goes By'?

Answer: as time goes by


Question: What modern-day country was ruled between 1902 and 1964 by Abdul Aziz Ibn Saud and his son, Emir Saud?

Answer:
ibn saud