def _op_method(self, data, extra_factor=1.0):
        r"""Operator method

        This method returns the scaled version of the proximity operator as
        given by Lemma 2.8 of [CW2005].

        Parameters
        ----------
        data : np.ndarray
            Input data array
        extra_factor : float
            Additional multiplication factor

        Returns
        -------
        np.ndarray result of the scaled proximity operator
        """
        return self.linear_op.adj_op(
            self.prox_op.op(self.linear_op.op(data), extra_factor=extra_factor)
        )