Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
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Question: vincenzo bellini (catania, november 3 1801 - puteaux, near paris, september 23 1835) was an italian composer and opera composer.

Answer: vincenzo bellini


Question: nightmare disorder, also known as "dream anxiety disorder", is a sleep disorder characterized by frequent nightmares.

Answer: nightmare disorder


Question: a federal monarchy is a federation of states with a single monarch as overall head of the federation, but also having lesser monarchs, or a republican system of government, in the various states joined to the federation.

Answer:
federal monarchy