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: nokogiri.rb
    path of file: ./repos/opensrs/lib/opensrs/xml_processor
    
    the code of the file until where you have to start completion: begin
  require 'nokogiri'
rescue LoadError => e
  warn 'Cannot find `nokogiri
    
      def self.sanitize(xml_string)
        doc = ::Nokogiri::XML(xml_string)
        doc.xpath("//item[@key='reg_username']").each do |node|
          node.content = 'FILTERED'
        end
        doc.xpath("//item[@key='reg_password']").each do |node|
          node.content = 'FILTERED'
        end
        doc.to_xml
      end