code: def start_file_logger(filename, name='database_manager', level=logging.DEBUG, format_string=None):
      
      if format_string is None:
          format_string = "%(asctime)s %(name)s:%(lineno)d [%(levelname)s]  %(message)s"
  
      global logger
      logger = logging.getLogger(name)
      logger.setLevel(level)
      handler = logging.FileHandler(filename)
      handler.setLevel(level)
      formatter = logging.Formatter(format_string, datefmt='%Y-%m-%d %H:%M:%S')
      handler.setFormatter(formatter)
      logger.addHandler(handler)
      return logger
docs: Add a stream log handler.
      Parameters
      ---------
      filename: string
          Name of the file to write logs to. Required.
      name: string
          Logger name. Default="parsl.executors.interchange"
      level: logging.LEVEL
          Set the logging level. Default=logging.DEBUG
          - format_string (string): Set the format string
      format_string: string
          Format string to use.
      Returns
      -------
          None.