code: def real_main(new_url=None,
                baseline_url=None,
                upload_build_id=None,
                upload_release_name=None):
      
      coordinator = workers.get_coordinator()
      fetch_worker.register(coordinator)
      coordinator.start()
  
      item = UrlPairDiff(
          new_url,
          baseline_url,
          upload_build_id,
          upload_release_name=upload_release_name,
          heartbeat=workers.PrintWorkflow)
      item.root = True
  
      coordinator.input_queue.put(item)
      coordinator.wait_one()
      coordinator.stop()
      coordinator.join()
docs: Runs the ur_pair_diff.