Alternative for depreciated AppUrlOpener and FancyURLopener

Question

I am a total Python novice and am trying to convert someone elses code from PY2 to PY3 that downloads some xml code and converts it, I am stuck on how to replace the AppUrlOpener

Towards the start there is

class AppUrlOpener(urllib.request.FancyURLopener):
    """Set user agent for downloads
    """
    version = 'Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36'

And further down

urllib.request._urlopener = AppUrlOpener()

I have tried replacing with

urllib.request._urlopener = urlopen()

but it tells me to use newer urlopen functions/methods.

Any suggestions what to try