[Someone]

It is the effect of making the example as short as possible. The price one pays is that it becomes pointless/silly (http://stackoverflow.com/questions/11704406/whats-the-point-...).

In C++, the keyword 'virtual' can be used to introduce a new virtual member function and to re-assert that a member function is virtual (http://stackoverflow.com/questions/4895294/c-virtual-keyword...). Using 'final virtual' only makes sense for the second use, but is legal in the first context because of the re-use of the 'virtual' keyword.