code: def getdefault(self):
          
  
          if not self.available:
              error('No supported downloaders available')
              print('\nPlease install one of the following:', file=sys.stderr)
              print(self.SUPPORTED, file=sys.stderr)
              sys.exit(1)
  
          default = Config.DOWNLOADER_DEFAULT
  
          if default in self.available:
              return default
          else:
              alternative = self.available[0]
              warning('Default downloader {!r} not available, using {!r} instead'
                      .format(Config.DOWNLOADER_DEFAULT, alternative))
              return alternative
docs: Return an available default downloader.