Blender python でCyclesにNode Groupを追加

import bpy


tree = bpy.data.materials['Material'].node_tree

def create_nodegroup():
    
    # create node group
    my_new_Group = bpy.data.node_groups.new('My_New_Group', 'ShaderNodeTree')

    # input
    mngInputs = my_new_Group.nodes.new('NodeGroupInput')
    mngInputs.location = (0,0)
    my_new_Group.inputs.new('NodeSocketFloat','my scale input')

    # output
    mngOutputs = my_new_Group.nodes.new('NodeGroupOutput')
    mngOutputs.location = (500,0)
    my_new_Group.outputs.new('NodeSocketFloat','my float output')
    my_new_Group.outputs.new('NodeSocketColor','my color output')



    # node in nodegroup
    texnode = my_new_Group.nodes.new('ShaderNodeTexWave')
    texnode.location = (200,0)
    
    # connect nodes
    my_new_Group.links.new(mngInputs.outputs[0],texnode.inputs[0])
    my_new_Group.links.new(texnode.outputs['Color'],mngOutputs.inputs['my color output'])
    
    return my_new_Group

################################################################
###################### Add New Node Group ######################
################################################################
groupnode = tree.nodes.new(type='ShaderNodeGroup')
groupnode.node_tree = create_nodegroup()