code: def default_asset_manager(self):
          
          cache_path = None
          cache_directory = self.config['CACHE_DIRECTORY']
          if cache_directory:
              cache_directory = cache_directory.format(version=__version__)
              cache_path = os.path.join(self.instance_path, cache_directory)
          return GitHubAssetManager(
              cache_path, self.config['STYLE_URLS'], self.quiet)
docs: Returns the default asset manager using the current config.
  
          This is only used if asset_manager is set to None in the constructor.