def _prune_neuron_at_index(self, index: int) -> None:
        """
        Set the weights (and biases) of a neuron at index in the penultimate layer of the neural network to zero

        :param index: An index of the penultimate layer
        """
        if self.layer_names is not None:
            layer = self._model.layers[len(self.layer_names) - 2]
        else:  # pragma: no cover
            raise ValueError("No layer names found.")
        weights, biases = layer.get_weights()
        weights[:, index] = np.zeros_like(weights[:, index])
        biases[index] = 0
        layer.set_weights([weights, biases])

        Set the weights (and biases) of a neuron at index in the penultimate layer of the neural network to zero

        :param index: An index of the penultimate layer
        
art/estimators/poison_mitigation/neural_cleanse/keras.py