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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def custom_background_code():
 """ 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). """

    while True:
        logger.info("Block %s / %s", str(Blockchain.Default().Height), str(Blockchain.Default().HeaderHeight))
        sleep(15)