[Zope] How do you check if some URL is present? Eg. isactive(http://www.stoonsdesign.dk)=?

Can somebody please tell me how I check if an URL is active or inactive...? I am going to use this to check all the external links on my own zopeserver if they are not active I will remove them... Stoons, WebMaster @ 3D Festival http://www.3dfestival.com (Yes, that was made using Zope!)