new version of song.rb. If you try song.artist in irb, there is no attribute artist, but it will work if you do song.get_the_artist.
new version of song.rb. If you try song.class_artist, the descriptor will give an error because the method is undefined.
new version of song.rb. If you try song.class_artist, the function will return the instance variable of @artist which is defined as 'Led Zeppelin'