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: language_tracking.rb
    path of file: ./repos/mushroom-observer/app/models
    
    the code of the file until where you have to start completion: # frozen_string_literal: tru
    
  def periodically_clean_up
    cutoff = 10.minutes.ago
    return unless !@@last_clean || @@last_clean < cutoff

    @@last_clean = Time.zone.now
    glob = tag_file("*")
    Dir.glob(glob).each do |file|
      File.delete(file) if File.mtime(file) < cutoff
    rescue StandardError
      # I've seen this fail because of files presumably being deleted by
      # another process between Dir.glob and File.mtime.
    end
  end