Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Q: Mr Barkis, Edward Murdstone and Tommy Traddles are all characters in which Charles Dickens novel?

A: charles dickens
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Q: Better known as an actor, who directed the film `A Bronx Tale`?

A: a bronx tale
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Q: In which European city would you have found Checkpoint Charlie?

A:
checkpoint charlie
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