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: git_user_default_ssh_config_check.rb
    path of file: ./repos/gitlabhq/lib/system_check/app
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module SystemCheck
  module App
    class GitUserDefaultSSHConfigCheck < SystemCheck::BaseCheck
      # These files are allowed in the .ssh directory. The `config` file is not
      # whi
    
      def show_error
        backup_dir = "~/gitlab-check-backup-#{Time.now.to_i}"

        instructions = forbidden_files.map do |filename|
          "sudo mv #{Shellwords.escape(filename)} #{backup_dir}"
        end

        try_fixing_it("mkdir #{backup_dir}", *instructions)
        for_more_information('doc/user/ssh.md#overriding-ssh-settings-on-the-gitlab-server')
        fix_and_rerun
      end