Updated: assignable_values can now humanize any given value, even if it's not the current attribute

You've always been able to access the humanized version for the current value like this:

Copysong = Song.new(:genre => 'pop')
song.humanized_genre # => 'Pop music'

You can now also retrieve the humanized version of any given value by passing it as an argument:

Copysong.humanized_genre('rock') # => 'Rock music'