TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Who directed the film Black Swan (in ballet)?

SOLUTION: black swan

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

SOLUTION: as time goes by

PROBLEM: Who played the Prince Regent in Blackadder the Third?

SOLUTION:
blackadder