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: custom.rb
    path of file: ./repos/backup/lib/backup/compressor
    
    the code of the file until where you have to start completion: module Backup
  module Compressor
    class Custom <
    
      def initialize(&block)
        load_defaults!

        instance_eval(&block) if block_given?

        @cmd = set_cmd
        @ext = set_ext
      end