[Zope] dtml <-> ZPT

I'd like to use the ShoppingCart from the Examples folder in Zope 2.5.1 and modify it. In the script getItem are the products, descriptions and prices. The price part looks like this: 'price' : 22.0} I'd like to replace it by something, which looks like this in DTML: <dtml-let a="price/currency"> <dtml-var a fmt="%.0f"> </dtml-let> I am a total newbie to ZPT and Python, so how can I achieve the above DTML in a Python script? the price/currency structure is needed, because the price is available as a property and the structure enables the user to select another currency. TIA for any help. Stephan