@property
    def Wzz(self):
        """Regularization matrix Wzz"""
        if getattr(self, '_Wzz', None) is None:
            self._Wzz = Utils.sdiag((self.mesh.vol*self.alpha_zz)**0.5)*self.mesh.faceDivz*self.mesh.cellGradz

            if self.indActive is None:
                Pac = Utils.speye(self.mesh.nC)[:,self.indActive]
                self._Wzz = Pac.T*self._Wzz*Pac

        return self._Wzz
dataset/ETHPy150Open simpeg/simpeg/SimPEG/Regularization.py/Tikhonov.Wzz/operator `is not` -> `is`