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: stale.rb
    path of file: ./repos/nanoc/nanoc-checking/lib/nanoc/checking/checks
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Nanoc
  module Checking
    module Checks
      # @api private
      class Stale < ::Nanoc::Checking::Check
     
    
        def run
          output_filenames.each do |f|
            next if pruner.filename_excluded?(f)
            next if item_rep_paths.include?(f)

            add_issue(
              'file without matching item',
              subject: f,
            )
          end
        end