xml_stylesheet_pi

# File lib/rss/xml-stylesheet.rb, line 13
    def xml_stylesheet_pi
      xsss = @xml_stylesheets.collect do |xss|
        pi = xss.to_s
        pi = nil if /\A\s*\z/ =~ pi
        pi
      end.compact
      xsss.push("") unless xsss.empty?
      xsss.join("\n")
    end