So it is easy to get at it. It should just be added to the methods parameter list. I just have to put this into a Python package and put it into the right directory in my Zope installation. That is why we have to restart Zope to install a new product. The second parameter is a tuple of methods from minimal that are used as constructors.
Constructors are the methods that adds the instance to the folder.
We dont want the method to be executed, we just want to tell Zope what method it is. Usually a form is used to add the product, but I don't do that here. Because that would make it less minimal. More about this later. This is the absolutely minimal class that I can think of that is a fully functional Zope Product.