code: def enqueue(self, job):
      
      if job.queue_name():
        raise EnqueueError("job %s already queued!" % job.job_id)
      new_len = self.redis.lpush(self.queue_name, job.serialize())
      job.notify_queued(self)
      return new_len
docs: Enqueue a job for later processing, returns the new length of the queue