How to use the x2paddle.core.fluid_code.Layer function in x2paddle

def gen_codes(self):
        codes = list()
        for layer in self.layers:
            if isinstance(layer, Layer):
                codes.append(layer.get_code())
            elif isinstance(layer, six.string_types):
                codes.append(layer)
        return codes

true_node = self.graph.get_node(node_name)
                    for i, in_name in enumerate(node.inputs):
                        in_node = graph_copy.get_node(in_name)
                        if hasattr(in_node, "is_nhwc") and in_node.is_nhwc:
                            if i == 0:
                                l = Layer()
                                l.op = "transpose"
                                l.inputs = true_node.fluid_code.layers[
                                    0].inputs["x"]
                                l.param_attr = {"perm": [0, 2, 3, 1]}
                                l.output = "nhwc_" + l.inputs.layer_name
                                true_node.fluid_code.layers[0].inputs[
                                    "x"] = l.output
                                true_node.fluid_code.layers.insert(0, l)
                            elif i == 1:
                                l = Layer()
                                l.op = "transpose"
                                l.inputs = true_node.fluid_code.layers[
                                    0].inputs["y"]
                                l.param_attr = {"perm": [0, 2, 3, 1]}
                                l.output = "nhwc_" + l.inputs.layer_name
                                true_node.fluid_code.layers[0].inputs[
                                    "y"] = l.output
                                true_node.fluid_code.layers.insert(0, l)
                            else:
                                raise Exception("Unexpected situation happend")
                    continue
                else:
                    for out_name in node.outputs:
                        out_node = self.graph.get_node(out_name)
                        if out_node.layer_type not in elementwise_ops:
                            assert out_node.fluid_code.layers[

def add_layer(self,
                  op,
                  inputs,
                  output,
                  param_attr=None,
                  is_custom_layer=False):
        layer = Layer()
        layer.op = op
        layer.is_custom_layer = is_custom_layer
        if inputs is not None:
            layer.inputs = inputs
        layer.output = output
        if param_attr is not None:
            layer.param_attr = param_attr
        self.layers.append(layer)