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: Which composer was married to Clara Wieck from 1840 until his death in 1856?

Answer: clara schumann

Question: Which singer played Billie Holiday in the 1972 film 'Lady Sings The Blues'?

Answer: lady sings the blues

Question: In which European capital is Bromma Airport?

Answer:
stockholm bromma airport