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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 luks_cleartext_holder(self):
 """Get wrapper to the unlocked luks cleartext device."""

        if not self.is_luks:
            return None
        for device in self._daemon:
            if device.luks_cleartext_slave == self:
                return device
        return None