Do I do something wrong here or I cannot override method upcase in String?

class String
   def upcase
     super.upcase
   end
end

"abc".upcase

Thanx for any help,
Bojan Mihelac

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Bojan Mihelac
Informatika Mihelac, Bojan Mihelac s.p.  |  www.informatikamihelac.com
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