Downloading from internet: How do I add a user/password to a proxy (only using packages that come by default with python)?

Question

I have the code below, that sets a proxy for a file download process.

How do I add a user/password (only using packages that come by default with python) ?

from http.client import HTTPResponse
from urllib import request, error

  

def setup_opener():
            if proxy:
                proxy_handler = request.ProxyHandler({proxy.protocol: proxy.host})
                auth = request.HTTPBasicAuthHandler()
                opener = request.build_opener(proxy_handler, auth, request.HTTPHandler)
                request.install_opener(opener)
setup_opener()