Useful for example to spread changes to the prompt, e.g. enabling or
        disabling colors.

def iter_walk_menus(self):
        """
        Useful for example to spread changes to the prompt, e.g. enabling or
        disabling colors.
        """
        yield self
        for item in self.name_to_command.values():
            if isinstance(item, _Menu):
                # "Generator delegation" ;)
                # https://docs.python.org/3/whatsnew/3.3.html#pep-380
                yield from item.iter_walk_menus()