text: from __future__ import print_function
  
  import os
  import requests
  import shutil
  import sys
  
  URL = 'http://ai.stanford.edu/%7Eamaas/data/sentiment/aclImdb_v1.tar.gz'
  DIR = os.path.expanduser('~/.cache/paddle/dataset/imdb')
  PATH = os.path.join(DIR, URL.split('/')[-1])
  CHUNK_SIZE = 4096
  
  # Download the dataset
  def download():
      if not os.path.exists(DIR):
          os.makedirs(DIR)
  
      retry = 0
      retry_limit = 3 
      while not os.path.exists(PATH):
          if retry < retry_limit:
              retry += 1
          else:
              raise RuntimeError("Cannot download {0} within retry limit {1}".
                                 format(URL, retry_limit))
          r = requests.get(URL, stream=True)
          total_length = r.headers.get('content-length')
  
          if total_length is None:
              with open(PATH, 'w') as f:
                  shutil.copyfileobj(r.raw, f)
          else:
              with open(PATH, 'wb') as f:
                  for data in r.iter_content(chunk_size=CHUNK_SIZE):
                      f.write(data)
  
      print("Download successful!")
  
  if __name__ == "__main__":
      download()
  