Set Wall Compound Layers Function

Thank you @Dimitar_Venkov! I just managed to create a node to change the Finish Layer to Membrane (which exludes the core layer)… However, when trying to change back from membrane to Finish, the core layer also gets edited. I´m currently trying (Im new to python) to use an IF statment to exclude the core layer when switching back to Finish, however i can´t manage to make it work.