code: def download(self):
          
          if os.path.isfile(self.archive_path):
              print("Use %r" % self.archive_path)
              with open(self.archive_path, "rb") as f:
                  content = f.read()
          else:
              print("Request: %r..." % self.URL)
              # Warning: HTTPS requests do not do any verification of the server's certificate.
              f = urlopen(self.URL)
              content = f.read()
              with open(self.archive_path, "wb") as out_file:
                  out_file.write(content)
  
          # Check SHA hash:
          current_sha1 = hashlib.sha1(content).hexdigest()
          assert current_sha1 == self.DOWNLOAD_SHA1, "Download sha1 value is wrong! SHA1 is: %r" % current_sha1
          print("Download SHA1: %r, ok." % current_sha1)
docs: Request url and return his content
          The Requested content will be cached into the default temp directory.