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: clean_html.rb
    path of file: ./repos/devdocs/lib/docs/filters/phpunit
    
    the code of the file until where you have to start completion: module Docs
  class Phpunit
    class CleanHtmlFilter < Filter
     
    
      def call
        @doc = at_css('.section') if not root_page?

        css('pre').each do |node|
          node['class'] = 'highlight'
          node['data-language'] = 'php'
        end

        if slug.match(/assertion|annotations|configuration/)
          css('h2').each do |node|
            node['id'] = node.content
          end
        end