docs: def file_logger(app, level=None):
      """
      Get file logger
      Returns configured fire logger ready to be attached to app
  
      :param app:         application instance
      :param level:       log this level
      :return:            RotatingFileHandler
      """
      path = os.path.join(os.getcwd(), 'var', 'logs',  'app.log')
  
      max_bytes = 1024 * 1024 * 2
      file_handler = RotatingFileHandler(
          filename=path,
          mode='a',
          maxBytes=max_bytes,
          backupCount=10
      )
  
      if level is None: level = logging.INFO
      file_handler.setLevel(level)
  
      log_format  = '%(asctime)s %(levelname)s: %(message)s'
      log_format += ' [in %(pathname)s:%(lineno)d]'
      file_handler.setFormatter(logging.Formatter(log_format))
  
      return file_handler