def _convert_identity(builder, node, graph, err):
    """
    convert to CoreML Linear Activation Layer:
    https://github.com/apple/coremltools/blob/655b3be5cc0d42c3c4fa49f0f0e4a93a26b3e492/mlmodel/format/NeuralNetwork.proto#L417
    """
    builder.add_activation(name=node.name, non_linearity='LINEAR',
        input_name=node.inputs[0], output_name=node.outputs[0], params=[1.0,
        0.0])
