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: Who won the 2011 Booker Prize for 'The Sense of an Ending'?

Answer: the sense of an ending


Question: Who stars in the TV series Californication?

Answer: californication


Question: Billy Piper played the travelling companion to the lead role in which TV series that played in Great Britain in 2005?

Answer:
billie piper