Could someone please show an example of the programmatic manipulation of property sheets for an instance of a Python class (not ZClass) derived from PropertyManager? I've looked at http://www.zope.org/Members/michel/Projects/Interfaces/PropertySheets and the pages it points to, which provide most of the information, and I'm sure I can read the code enough to figure out the rest, but it would be really helpful to have an example of some interesting manipulations. Specifically, I want to add a few property sheets, then define a few properties for each of those sheets (with initial values). Ideally, I'd like to do this generically somehow as part of my class -- especially the initial values -- rather than having to initialize every property of every sheet for each instance.