code: function retryJob(job, when) {
    when = when || 'later';
  
    // Reaching maxRetries?
    if (job.req.retries >= this.options.maxRetries)
      return;
  
    // Dropping from remains
    delete this.remains[job.id];
  
    // Request
    job.req.retries++;
    job.state.retrying = true;
  
    // Adding to the queue again
    this.queue[when === 'now' ? 'unshift' : 'push'](job);
  
    this.emit('job:retry', job, when);
  }
docs: Retrying a job