[Zope] Display the icon of a meta_type

Hello, I am facing a little problem ;-) I am using a ZCatalog object on my site. When I do a query, I want the results do display the meta_type of the document found with it's icon. I've seen that on Zope.org and loved this idea... the only problem is that it is a method on zope.org that does the trick (<!--#var "icon_for_meta_type(REQUEST,meta_type=meta_type)"-->) and I don't have the source for it. Thank you for your help. Best regards, Gérard Métrailler Jr.