python :create vector3 and link to materials

Hey guys, I’m looking for your help again ! i want to use the python  to create MaterialExpressionConstant3Vector and conncet to the mat‘s  Emissive Color 。this my code 。

material_body = unreal.load_asset(’/Game/StarterContent/Props/Materials/M_Rock’)
material_body.modify()
material_body_emissive = unreal.MaterialExpressionConstant3Vector(material_body)
vector_color = unreal.LinearColor(r=0.0, g=0.0, b=0.0)
material_body_emissive.set_editor_property(‘constant’, vector_color)

unreal.MaterialEditingLibrary.connect_material_expressions()

i dont konw how to link …how can i do ?

​​​​​​​thank you !