src/vs/workbench/contrib/notebook/browser/services/notebookServiceImpl.ts/ModelData/constructor
class ModelData:	constructor(
		readonly model: NotebookTextModel,
		onWillDispose: (model: INotebookTextModel) => void
	) {
		this._modelEventListeners.add(model.onWillDispose(() => onWillDispose(model)));
	}