like in the wild? :)
The cars and animal routine never really helped me much either. I have observed inheritance in the wild, a media class inherited by specific mediaaccessors (nfs,ftp,smb,stonefs) - viola ~ an agent calling methods of media class cares not about it's genesis.

Abstract rate counters, have been spotted nesting with children who delight in measuring and playing with a variety of data such as;

• Time (x)MB over 100TX
• Frames (h) (m) (s) (f) NTSC
• Time (x)GB DLT write
• GigaBytes (h)(m)(s) PAL @ 720x576x24

The children are shallow creatures , exhibiting a megre ammount of self.

package Counter::FramesHMSFNTSC;
@ISA( Counter );
init( 
        hours=>[],
        minutes=>[ hours=>60 ],
        seconds=>[ minutes=>60 ],
        frames=>[ seconds=>30],
        atomic=>'frames',
        );
[download]

Pretty gross perhaps, but very lazy since these are usually constant things.