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.

[EX Q]: fair use is the idea that it should be okay for a person to reuse something that another person has created, in certain amounts and for certain purposes, without breaking the law.
[EX A]: fair use

[EX Q]: the 1939–40 nhl season was the 23rd season for the national hockey league.
[EX A]: 1939–40 nhl season

[EX Q]: nexon corporation is a korean gaming corporation and developer of online games and mmorpgs.
[EX A]:
nexon