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