code: def custom_background_code():
      
      while True:
          logger.info("Block %s / %s", str(Blockchain.Default().Height), str(Blockchain.Default().HeaderHeight))
          sleep(15)
docs: Custom code run in a background thread. Prints the current block height.
  
      This function is run in a daemonized thread, which means it can be instantly killed at any
      moment, whenever the main thread quits. If you need more safety, don't use a  daemonized
      thread and handle exiting this thread in another way (eg. with signals and events).