public function data($key = null) {
		$data = $this->body['data'];
		if ($key !== null) {
			foreach (explode('.', $key) as $part) {
				if (isset($data[$part])) {
					$data = $data[$part];
				} else {
					$data = null;
					break;
				}
			}
		}
		return $data;
	}