Atom xml generation in Kalimba

kalimba_atom.rb

def _rss
  if @last_update
    self << @b.feed(
        'xmlns' => 'http://www.w3.org/2005/Atom') do |f|
      f.title 'Kalimba'
      f.link :href => CONFIG[:canonical_url]
      id = CONFIG[:canonical_url]
      id = "#{id}/" unless id.end_with?'/'
      f.id id
      f.link :rel => 'self', :type => 'application/atom+xml', 
             :href=> "#{CONFIG[:canonical_url]}#{R(Rss)}"
      f.subtitle CONFIG[:tagline]
      f.updated @last_update.created_at.utc.strftime(
                                     "%Y-%m-%dT%H:%S:%MZ")
      f.author do |a|
        a.name CONFIG[:author_name]
        a.email CONFIG[:author_email]
        a.uri CONFIG[:author_uri]
      end
      f.generator 'Kalimba'
      @articles.each do |article, preview_row, preview|
        f.entry do |i|
          i.title article.title
          i.link article.link, 
            :href => Kalimba::Models::Article.
                              normalize_url(article.link)
          id = Kalimba::Models::Article.
                              normalize_url(article.link)
          id = "#{id}/" unless id.end_with?'/'
          i.id id
          if preview_row
            i.updated preview_row.created_at.utc.strftime(
                                      "%Y-%m-%dT%H:%S:%MZ")
            i.published preview_row.created_at.utc.strftime(
                                      "%Y-%m-%dT%H:%S:%MZ")
          else
            i.updated @last_update.created_at.utc.strftime(
                                      "%Y-%m-%dT%H:%S:%MZ")
            i.published @last_update.created_at.utc.strftime(
                                      "%Y-%m-%dT%H:%S:%MZ")
          end
          i.author do |author|
            author.name article.author
            author.uri article.author_link
          end
          if preview
            content = render(:_rss_content, article, preview)
          end
          if content
            i.content content, :type => 'html'
          end
          if preview
            i.summary preview.description, :type => 'html'
          end
        end
      end
    end
  end
end