def is_compressed(path):
        """Test if path represents compressed file(s).

        :param str path: Path to file(s).
        :return: String specifying compression type if compressed, "" otherwise.
        :rtype: :py:class:`str`
        """
        if path.endswith(".zip"):
            return "zip"
        elif path.endswith(".tar.gz"):
            return "tar.gz"
        elif path.endswith(".tar.bz2"):
            return "tar.bz2"
        elif path.endswith(".gz"):
            return "gz"
        elif path.endswith(".bz2"):
            return "bz2"
        elif path.endswith(".tar"):
            return "tar"
        return ""