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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def change_name(self, username):

 """ changes the username to given username, throws exception if username used """

        self.release_name()

        try:
            self.server.register_name(username)
        except UsernameInUseException:
            logging.log(', '.join(self.server.registered_names))
            self.server.register_name(self.name)
            raise
            
        self.name = username