code: def pipfaster_download_cacher(index_urls):
      
      from pip._internal import download
      orig = download._download_http_url
      patched_fn = get_patched_download_http_url(orig, index_urls)
      return patched(vars(download), {'_download_http_url': patched_fn})
docs: vanilla pip stores a cache of the http session in its cache and not the
      wheel files.  We intercept the download and save those files into our
      cache