def _predict_label(self, x_0: np.ndarray) -> np.signedinteger:
        """
        Helper method to predict label for x_0

        :param x_0: An array with the original input
        :return: Predicted label
        """
        if self.enable_clipped:
            x_0 = np.clip(x_0, self.clip_min, self.clip_max)
        pred = self.estimator.predict(np.expand_dims(x_0, axis=0), batch_size=self.batch_size)
        return np.argmax(pred)

        Helper method to predict label for x_0

        :param x_0: An array with the original input
        :return: Predicted label
        
art/attacks/evasion/sign_opt.py