Parsers a single line of text and returns an AudioClipSpec

        Line format:
            <number> <number> [<text>]

        Returns: list(AudioClipSpec) or None

def _parseLine(cls, line):
        """Parsers a single line of text and returns an AudioClipSpec

        Line format:
            <number> <number> [<text>]

        Returns: list(AudioClipSpec) or None
        """
        r = cls._PROG.match(line)

        if not r:
            raise ValueError("Error: parsing '%s'. Correct: \"<number> <number> [<text>]\"" % line)

        d = r.groupdict()

        if len(d['begin']) == 0 or len(d['end']) == 0:
            raise ValueError("Error: parsing '%s'. Correct: \"<number> <number> [<text>]\"" % line)
        
        return AudioClipSpec(d['begin'], d['end'], d['text'].strip())