private function getExtension($name)
	{
		if (class_exists('Twig_Extensions_Extension_' . $name)) {
			$name = 'Twig_Extensions_Extension_' . $name;
		}
		elseif (class_exists('Twig_Extensions_Extension_' . ucfirst(strtolower($name)))) {
			$name = 'Twig_Extensions_Extension_' . ucfirst(strtolower($name));
		}
		elseif (!class_exists($name)) {
			throw new InvalidConfigException('Twig extension "' . $name . '" not declared.');
		}
		return new $name();
	}