@property
    def Ws(self):
        """Regularization matrix Ws"""
        if getattr(self,'_Ws', None) is not None:
            self._Ws = Utils.sdiag((self.mesh.vol*self.alpha_s)**0.5)
            if self.indActive is not None:
                Pac = Utils.speye(self.mesh.nC)[:,self.indActive]
                self._Ws = Pac.T * self._Ws * Pac
        return self._Ws
dataset/ETHPy150Open simpeg/simpeg/SimPEG/Regularization.py/Tikhonov.Ws/operator `is` -> `is not`