You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: xml-stylesheet.rb
    path of file: ./repos/ruby-packer/ruby/lib/rss
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
require_relative "utils"

module RSS

  module XMLStyleSheetMixin
    attr_accessor :xml_stylesheets
    
    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
  end