Uninstall.php for my plugin

I keep finding conflicting ways to write an uninstall.php file for your plugin. I know how to delete_options, I’m just not sure If the beginning of my uninstall.php is correct. I’ve found two articles that say to do it differently:

Codex:

//if uninstall not called from WordPress exit
if ( !defined( 'WP_UNINSTALL_PLUGIN' ) )
	exit ();

delete_option('example');

and alternate source (wptuts):

if(defined('WP_UNINSTALL_PLUGIN') ){  

  //delete options, tables or anything else  

}

So which is the correct way? I’m leaning towards the wptuts way, but only because it seems to make a bit more sense to me.
Thanks guys