code: def download(cls, root, check=None):
          
          path = os.path.join(root, cls.name)
          check = path if check is None else check
          if not os.path.isdir(check):
              for url in cls.urls:
                  if isinstance(url, tuple):
                      url, filename = url
                  else:
                      filename = os.path.basename(url)
                  zpath = os.path.join(path, filename)
                  if not os.path.isfile(zpath):
                      if not os.path.exists(os.path.dirname(zpath)):
                          os.makedirs(os.path.dirname(zpath))
                      print('downloading {}'.format(filename))
                      download_from_url(url, zpath)
                  zroot, ext = os.path.splitext(zpath)
                  _, ext_inner = os.path.splitext(zroot)
                  if ext == '.zip':
                      with zipfile.ZipFile(zpath, 'r') as zfile:
                          print('extracting')
                          zfile.extractall(path)
                  # tarfile cannot handle bare .gz files
                  elif ext == '.tgz' or ext == '.gz' and ext_inner == '.tar':
                      with tarfile.open(zpath, 'r:gz') as tar:
                          dirs = [member for member in tar.getmembers()]
                          tar.extractall(path=path, members=dirs)
                  elif ext == '.gz':
                      with gzip.open(zpath, 'rb') as gz:
                          with open(zroot, 'wb') as uncompressed:
                              shutil.copyfileobj(gz, uncompressed)
  
          return os.path.join(path, cls.dirname)
docs: Download and unzip an online archive (.zip, .gz, or .tgz).
  
          Arguments:
              root (str): Folder to download data to.
              check (str or None): Folder whose existence indicates
                  that the dataset has already been downloaded, or
                  None to check the existence of root/{cls.name}.
  
          Returns:
              str: Path to extracted dataset.