my $cd = Music->new(name => 'Four Seasons', arist => 'Vivaldi', rating => 7,);

##</code><code>##

If you have a reference to a hash-based object, say, $objref, and you're using an attribute such as $objref->{_weirdness_factor}, then chances are that somewhere in the heat of coding, you'll accidentally write something like $objref->{_wierdness_factor}++.