Specifying no-proxy for urllib2

[Anand]

Hi

 How can I tell urllib2 that certain addresses are not
to be chained to the ProxyHandler ? I am behind a firewall
but for browsing internal servers I dont need to go through
it. In Browsers(netscape etc), you specify this in an entry
named 'No proxy for:'.

 How do I do this for urllib2/urllib. I think there ought
to be some specific headers in the Request class to specify
this.

Thanks

Anand Pillai