code: def check_filepath(self, path, filename):
          
          settings_path = os.path.join(path, filename)
  
          if not os.path.exists(settings_path) or \
             not os.path.isfile(settings_path):
              msg = "Unable to find settings file: {}"
              raise SettingsBackendError(msg.format(settings_path))
  
          return settings_path
docs: Check and return the final filepath to settings
  
          Args:
              path (str): Directory path where to search for settings file.
              filename (str): Filename to use to search for settings file.
  
          Raises:
              boussole.exceptions.SettingsBackendError: If determined filepath
                  does not exists or is a directory.
  
          Returns:
              string: Settings file path, joining given path and filename.