docs: def download_url(url, destination):
      """
      Download an external URL to the destination
      """
      from settings import VALID_IMAGE_EXTENSIONS
      base_name, ext = os.path.splitext(url)
      ext = ext.lstrip('.')
  
      if ext not in VALID_IMAGE_EXTENSIONS:
          raise Exception("Invalid image extension")
  
      base_path, filename = os.path.split(destination)
      os.makedirs(base_path)
      urllib.urlretrieve(url, destination)