docs: def init_logger_file(log_file, log_level='INFO'):
      """ Append a FileHandler to the root logger.
      :param str log_file: Path to the log file
      :param str log_level: Logging level
      """
      log_level = LOG_LEVELS[log_level] if log_level in LOG_LEVELS.keys() else logging.INFO
  
      ROOT_LOG.setLevel(log_level)
  
      file_handle = logging.FileHandler(log_file)
      file_handle.setLevel(log_level)
      file_handle.setFormatter(formatter)
      ROOT_LOG.addHandler(file_handle)