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: queue_classic_adapter.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/activejob-5.0.3/lib/active_job/queue_adapters
    
    the code of the file until where you have to start completion: require 'queue_classic'

module ActiveJob
  module QueueAdapters
    # == queue_classic adapter for Active Job
    #
    # queue_classic
    
      def enqueue_at(job, timestamp) #:nodoc:
        queue = build_queue(job.queue_name)
        unless queue.respond_to?(:enqueue_at)
          raise NotImplementedError, 'To be able to schedule jobs with queue_classic ' \
            'the QC::Queue needs to respond to `enqueue_at(timestamp, method, *args)`. ' \
            'You can implement this yourself or you can use the queue_classic-later gem.'
        end