src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts/NotebookContribution/constructor
class NotebookContribution:	constructor(
		@IUndoRedoService undoRedoService: IUndoRedoService,
		@IConfigurationService configurationService: IConfigurationService,
	) {
		super();

		const undoRedoPerCell = configurationService.getValue<boolean>(UndoRedoPerCell);

		this._register(undoRedoService.registerUriComparisonKeyComputer(CellUri.scheme, {
			getComparisonKey: (uri: URI): string => {
				if (undoRedoPerCell) {
					return uri.toString();
				}
				return NotebookContribution._getCellUndoRedoComparisonKey(uri);
			}
		}));
	}