language specification in fenced code blocks

[wedens]

GFM has support for specifying language:

require 'redcarpet'
markdown = Redcarpet.new("Hello World!")
puts markdown.to_html

and it renders it to

<pre><code class="ruby">require &#39;redcarpet&#39;
markdown = Redcarpet.new(&quot;Hello World!&quot;)
puts markdown.to_html
</code></pre>

How can i implement this behaviour with pegdown? What I want is this class="ruby" inside code tag.

[wedens]

found #20 issue can be closed