Reader::readGuid PHP Метод

    public function readGuid()
    {
        $tag = $this->stream->getc();
        switch ($tag) {
            case Tags::TagNull:
                return null;
            case Tags::TagGuid:
                return $this->readGuidWithoutTag();
            case Tags::TagRef:
                return $this->readRef();
            default:
                throw $this->unexpectedTag($tag);
        }
    }