Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
--------
Question: Who has written a series of novels, entitled The Dark Tower, of which the first, in 1982, was entitled, The Gunslinger?

Answer: the dark tower


Question: What is the name of the US electric car manufacturer, founded in 2003, whose cars include the Model S and the Model X?

Answer: tesla model s


Question: Amerigo Vespucci airport is in which city?

Answer:
florence airport, peretola