def is_valid_multiply_node(node):
    return (isinstance(node, bpy.types.ShaderNodeMixRGB) and (node.blend_type == 'MULTIPLY') and (len(node.inputs) == 3))
def is_valid_multiply_node(node):
    return (isinstance(node, bpy.types.ShaderNodeMixRGB) and (node.blend_type == 'MULTIPLY') and (len(node.inputs) == 3))