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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 mask(self, mask):
 """ The mask values. Must be an array or a boolean scalar."""

        check_class(mask, (np.ndarray, bool, np.bool_))
        if isinstance(mask, (bool, np.bool_)):
            self._mask = bool(mask)
        else:
            self._mask = mask