Delegate a rule to another class which instantiates a Klein app

    This also memoizes the resource instance on the handler function itself

def enter(clsQname):
    """
    Delegate a rule to another class which instantiates a Klein app

    This also memoizes the resource instance on the handler function itself
    """
    def wrapper(routeHandler):
        @functools.wraps(routeHandler)
        def inner(self, request, *a, **kw):
            if getattr(inner, '_subKlein', None) is None:
                cls = namedAny(clsQname)
                inner._subKlein = cls().app.resource()
            return routeHandler(self, request, inner._subKlein, *a, **kw)
        inner._subKleinQname = clsQname
        return inner
    return wrapper