@staticmethod
def _structure_parse_qal_xpath(_qal_xpath):
    """Parse the trailing attribute identifier from the QAL xpath string. ":" isn't allowed in xpath.

        :param str _qal_xpath: QAL xpath string. Ex. "library/books/book | library/books"
        """
    _parts = _qal_xpath.split('::')
    if len(_parts) == 2:
        return _parts[0], _parts[1]
    else:
        return _qal_xpath, None
