'Return front, attrs, close, text 4-tuple result of parsing XML element
string *line*.'

@classmethod
def _parse_line(cls, line):

    match = cls._xml_elm_line_patt.match(line)
    (front, attrs, close, text) = [match.group(n) for n in range(1, 5)]
    return (front, attrs, close, text)
