docs: def download(url: str, filename: str,
               skip_cert_verify: bool = True) -> None:
      """
      Downloads a URL to a file.
  
      Args:
          url: URL to download from
          filename: file to save to
          skip_cert_verify: skip SSL certificate check?
      """
      log.info("Downloading from {} to {}", url, filename)
  
      # urllib.request.urlretrieve(url, filename)
      # ... sometimes fails (e.g. downloading
      # https://www.openssl.org/source/openssl-1.1.0g.tar.gz under Windows) with:
      # ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:777)  # noqa
      # ... due to this certificate root problem (probably because OpenSSL
      #     [used by Python] doesn't play entirely by the same rules as others?):
      # https://stackoverflow.com/questions/27804710
      # So:
  
      ctx = ssl.create_default_context()  # type: ssl.SSLContext
      if skip_cert_verify:
          log.debug("Skipping SSL certificate check for " + url)
          ctx.check_hostname = False
          ctx.verify_mode = ssl.CERT_NONE
      with urllib.request.urlopen(url, context=ctx) as u, open(filename,
                                                               'wb') as f:  # noqa
          f.write(u.read())