(builder, node, graph, err)
convert to CoreML Flatten Layer:
    https://github.com/apple/coremltools/blob/655b3be5cc0d42c3c4fa49f0f0e4a93a26b3e492/mlmodel/format/NeuralNetwork.proto#L4826
convert to CoreML Flatten Layer:
    https://github.com/apple/coremltools/blob/655b3be5cc0d42c3c4fa49f0f0e4a93a26b3e492/mlmodel/format/NeuralNetwork.proto#L4826
convert to CoreML Flatten Layer : https : // github . com / apple / coremltools / blob / 655b3be5cc0d42c3c4fa49f0f0e4a93a26b3e492 / mlmodel / format / NeuralNetwork . proto#L4826
def _convert_flatten(builder, node, graph, err):
    '''
    convert to CoreML Flatten Layer:
    https://github.com/apple/coremltools/blob/655b3be5cc0d42c3c4fa49f0f0e4a93a26b3e492/mlmodel/format/NeuralNetwork.proto#L4826
    '''
    axis = node.attrs.get('axis', 1)
    builder.add_flatten_to_2d(
        name=node.name,
        input_name=node.inputs[0],
        output_name=node.outputs[0],
        axis=axis
    )
def _convert_flatten ( builder , node , graph , err ) : axis = node . attrs . get ( 'axis' , 1 ) builder . add_flatten_to_2d ( name = node . name , input_name = node . inputs [ 0 ] , output_name = node . outputs [ 0 ] , axis = axis )