public function save($group, $destination = null)
	{
		if ($destination === null)
		{
			$destination = $group;
		}

		if ( ! $this->has($group))
		{
			throw new \RuntimeException('Unable to save non-existig config group: '.$group);
		}

		$destination = $this->ensureDefaultFormat($destination);
		$format = pathinfo($destination, PATHINFO_EXTENSION);
		$handler = $this->getHandler($format);
		$data = $this->get($group);
		$output = $handler->format($data);
		$path = $this->findDestination($destination);

		if ( ! $path)
		{
			throw new \RuntimeException(sprintf('Could not save group "%" as "%s".', $group, $destination));
		}

		return file_put_contents($path, $output);
	}