I'm currently building a GO JS floor planner based on this sample (https://gojs.net/latest/projects/floorplanner/FloorPlanner.html). When the user places walls and they connect to each other, I want to make a room out of the four walls. I want to fill out the area that was shaped by the 4 walls. I know this is in the second-floor planner but I just want to add this feature to the old one and I don't know TypeScript. Can someone help me, how should I do it?