def add_lrn(self, name, input_name, output_name, alpha, beta, local_size, k=1.0):
        """
        Add a LRN (local response normalization) layer. Supports "across" channels normalization.
        Refer to the ``LRNLayerParams`` message in the specification (NeuralNetwork.proto) for more details.

        Parameters
        ----------
        name: str
            The name of this layer.

        input_name: str
            The input blob name of this layer.
        output_name: str
            The output blob name of this layer.
        alpha: float
            multiplicative constant in the denominator.
        beta: float
            exponent of the normalizing term in the denominator.
        k: float
            bias term in the denominator. Must be positive.
        local_size: int
            size of the neighborhood along the channel axis.

        See Also
        --------
        add_l2_normalize, add_mvn
        """
        spec_layer = self._add_generic_layer(name, [input_name], [output_name])
        spec_layer_params = spec_layer.lrn
        spec_layer_params.alpha = alpha
        spec_layer_params.beta = beta
        spec_layer_params.localSize = local_size
        spec_layer_params.k = k
        return spec_layer

        Add a LRN (local response normalization) layer. Supports "across" channels normalization.
        Refer to the ``LRNLayerParams`` message in the specification (NeuralNetwork.proto) for more details.

        Parameters
        ----------
        name: str
            The name of this layer.

        input_name: str
            The input blob name of this layer.
        output_name: str
            The output blob name of this layer.
        alpha: float
            multiplicative constant in the denominator.
        beta: float
            exponent of the normalizing term in the denominator.
        k: float
            bias term in the denominator. Must be positive.
        local_size: int
            size of the neighborhood along the channel axis.

        See Also
        --------
        add_l2_normalize, add_mvn
        
coremltools/models/neural_network/builder.py