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: atomic_markable_reference.rb
    path of file: ./repos/brew/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.1.4/lib/concurrent/atomic
    
    the code of the file until where you have to start completion: module Concurrent
  # An atomic reference which maintain
    
    def try_update!
      old_val, old_mark = reference
      new_val, new_mark = yield old_val, old_mark

      unless compare_and_set old_val, new_val, old_mark, new_mark
        fail ::Concurrent::ConcurrentUpdateError,
             'AtomicMarkableReference: Update failed due to race condition.',
             'Note: If you would like to guarantee an update, please use ' +
                 'the `AtomicMarkableReference#update` method.'
      end