print   $gen->rss([itunes => "http://www.itunes.com/dtds/podcast-1.0.dtd"], {version => '2.0'});

##</code><code>##

<itunes:rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0" />

##</code><code>##

<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0">