text: """Prepare Cityscapes dataset"""
  import os
  import sys
  import argparse
  import zipfile
  
  cur_path = os.path.abspath(os.path.dirname(__file__))
  root_path = os.path.split(os.path.split(os.path.split(cur_path)[0])[0])[0]
  sys.path.append(root_path)
  
  from segmentron.utils import makedirs, check_sha1
  
  _TARGET_DIR = os.path.expanduser('~/.torch/datasets/citys')
  
  
  def parse_args():
      parser = argparse.ArgumentParser(
          description='Initialize ADE20K dataset.',
          epilog='Example: python prepare_cityscapes.py',
          formatter_class=argparse.ArgumentDefaultsHelpFormatter)
      parser.add_argument('--download-dir', default=None, help='dataset directory on disk')
      args = parser.parse_args()
      return args
  
  
  def download_city(path, overwrite=False):
      _CITY_DOWNLOAD_URLS = [
          ('gtFine_trainvaltest.zip', '99f532cb1af174f5fcc4c5bc8feea8c66246ddbc'),
          ('leftImg8bit_trainvaltest.zip', '2c0b77ce9933cc635adda307fbba5566f5d9d404')]
      download_dir = os.path.join(path, 'downloads')
      makedirs(download_dir)
      for filename, checksum in _CITY_DOWNLOAD_URLS:
          if not check_sha1(filename, checksum):
              raise UserWarning('File {} is downloaded but the content hash does not match. ' \
                                'The repo may be outdated or download may be incomplete. ' \
                                'If the "repo_url" is overridden, consider switching to ' \
                                'the default repo.'.format(filename))
          # extract
          with zipfile.ZipFile(filename, "r") as zip_ref:
              zip_ref.extractall(path=path)
          print("Extracted", filename)
  
  
  if __name__ == '__main__':
      args = parse_args()
      makedirs(os.path.expanduser('~/.torch/datasets'))
      if args.download_dir is not None:
          if os.path.isdir(_TARGET_DIR):
              os.remove(_TARGET_DIR)
          # make symlink
          os.symlink(args.download_dir, _TARGET_DIR)
      else:
          download_city(_TARGET_DIR, overwrite=False)
  