! @brief Increase logging level for a set of subloggers.

def _increase_logging(self, loggers):
        """! @brief Increase logging level for a set of subloggers."""
        if self._log_level_delta <= 0:
            level = max(1, self._default_log_level + self._log_level_delta - 10)
            for logger in loggers:
                logging.getLogger(logger).setLevel(level)