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: fileutils.rb
    path of file: ./repos/ruby/lib
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

begin
  require 'rbconfig'
rescue LoadError
  # for make rjit-headers
end

# Namespace for
    
    def postorder_traverse
      if directory?
        begin
          children = entries()
        rescue Errno::EACCES
          # Failed to get the list of children.
          # Assuming there is no children, try to process the parent directory.
          yield self
          return
        end