Material setting by Python script

I want to make a material like “picture 1”.
This material connected “constant3Vector” and “basecolor”.((R,G,B)=(0.2,0.3,0.5))
A Python script I made is showed below.(picture3)
This script connect “constant3Vector” and “basecolor” but the value of “constant3Vector” is (R,G,B)=(0,0,0).(picture 2)

I want you to tell me how to connect correctly.

#######################
import unreal

asset_path=“/Game”
mat_name=a

assetTools=unreal.AssetToolHelpers.get_asset_tools()
mf=unreal.MaterialFactoryNew()
material=assetTools.create_asset(“%s” % mat_name,”%s/test % asset_path, unreal.Material,mf)

basecolor=unreal.MaterialEditingLibrary.create_material_expression(material,unreal.MaterialExpressionConstant3Vector,-180,200)
unreal.MaterialEditingLibrary.connect_material_property(basecolor,””,unreal.MaterialProperty.MP_BASECOLOR)
basecolor.set_editor_property(“R”,0.2)
basecolor.set_editor_property(“G”,0.3)
basecolor.set_editor_property(“B”,0.5)
############################