Trampoline inheritance is something of a nuissance because all of the
base class methods need to be repeated.  I was doing this with some
defines that shoehorned common methods into each Member subclass, but
that was messy.

This approach (using "Curiously Recursive Templates") is nicer: each
PyWhatever class is templated with its base class, so that
PyFirmNoProd<FirmNoProd> ends up with inheritance path:

    PyFirmNoProd<FirmNoProd> : PyFirm<FirmNoProd> : PyAgent<FirmNoProd> :
    PyMember<FirmNoProd> : FirmNoProd : Firm : Agent : Member

This is still a lot of duplication, but it's mainly at the compiler
level which makes maintenance easier and keeps the code a bit cleaner.