docs: def dl_file(url, dest, chunk_size=6553):
      """Download `url` to `dest`"""
      import urllib3
      http = urllib3.PoolManager()
      r = http.request('GET', url, preload_content=False)
      with dest.open('wb') as out:
          while True:
              data = r.read(chunk_size)
              if data is None or len(data) == 0:
                  break
              out.write(data)
      r.release_conn()