def start_file_logger(self, name, log_file_level=logging.DEBUG, log_file_path='./'):
        """Start file logging."""

        log_file_path = os.path.expanduser(log_file_path) / '{}.log'.format(name)
        logdir = log_file_path.parent

        try:
            logdir.mkdir(parents=True, exist_ok=True)

            # If the log file exists, backs it up before creating a new file handler
            if log_file_path.exists():
                strtime = datetime.datetime.utcnow().strftime('%Y-%m-%d_%H:%M:%S')
                shutil.move(log_file_path, log_file_path + '.' + strtime)

            self.fh = TimedRotatingFileHandler(str(log_file_path), when='midnight', utc=True)
            self.fh.suffix = '%Y-%m-%d_%H:%M:%S'
        except (IOError, OSError) as ee:
            warnings.warn('log file {0!r} could not be opened for writing: '
                          '{1}'.format(log_file_path, ee), RuntimeWarning)
        else:
            self.fh.setFormatter(fmt)
            self.addHandler(self.fh)
            self.fh.setLevel(log_file_level)

        self.log_filename = log_file_path
Start file logging.