Special property containing functions to be lazily-evaluated.

def _attr_func_(self):
        "Special property containing functions to be lazily-evaluated."

        try:
            return self.__attr_func

        except AttributeError:
            self.__attr_func = type(
                ''.join([type(self).__name__, 'EmptyFuncs']),
                (),
                {
                    '__module__': type(self).__module__,
                    '__slots__': ()
                }
            )()
            return self.__attr_func