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: revision.rb
    path of file: ./repos/hexapdf/lib/hexapdf
    
    the code of the file until where you have to start completion: # -*- encoding: utf-8; frozen_string_literal: true 
    
    def object(ref)
      if ref.respond_to?(:oid)
        oid = ref.oid
        gen = ref.gen
      else
        oid = ref
      end