def require_setting(self, name, feature="this feature"):
        """Raises an exception if the given app setting is not defined."""
        if not self.application.settings.get(name):
            raise Exception("You must define the '%s' setting in your "
                            "application to use %s" % (name, feature))
Raises an exception if the given app setting is not defined.
recipes/Python/576906_Python_3_WSGI_Server/recipe-576906.py