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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 _wave(self):
 """Return a wave.Wave_read instance from the ``wave`` module."""

        try:
            return wave.open(StringIO(self.contents))
        except wave.Error, err:
            err.message += "\nInvalid wave file: %s" % self
            err.args = (err.message,)
            raise