def log(self, txt: str) -> bool:
        """ Log txt (if any) to the log file (if any). Return value indicates whether it is ok to terminate on the first
        error or whether we need to continue processing.

        :param txt: text to log.
        :return: True if we aren't logging, False if we are.
        """
        self.nerrors += 1
        if self._logfile is not None:
            print(txt, file=self._logfile)
        return not self.logging