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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _parse_timeframe_line(self, line):
 """Parse timeframe line and return start and end timestamps."""

        tf = self._validate_timeframe_line(line)
        if not tf:
            raise MalformedCaptionError('Invalid time format')

        return tf.group(1), tf.group(2)