[Twisted-web] simple proxy example?

[Wendell Turner]

The webdownload.py script in Abe Fettig's book works fine for
directly connected machines.  I would like to modify it to use a
proxy.  Most of the examples in the twisted docs seem to show
how to write a proxy, not how to use one.

To modify that example to use a proxy, do I need to use a
ProxyClientFactory instead of the HTTPDownloader?  I tried that,
but it needs 7 arguments, and I could not tell what they should
be.

Or do I just set the factory.protocol to proxy.Proxy?  If so,
where do I tell it the proxy's address & port?

Is there a (simple(!)) twisted web page retrieval script that
uses (i.e. runs behind) a proxy server that I could use to start
with?

Thanks,

Wendell