Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
--------
Question: Which country mainly makes up the Horn of Africa?

Answer: africa


Question: Who composed the opera 'Albert Herring' in 1947?

Answer: albert herring


Question: In which Verdi opera do the gypsies sing the 'Anvil Chorus'?

Answer:
anvil chorus