src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts/NotebookEditorWidget/setEditorDecorations
class NotebookEditorWidget:	setEditorDecorations(key: string, range: ICellRange): void {
		if (!this.viewModel) {
			return;
		}

		// create css style for the decoration
		if (!this._editorStyleSheets.has(key)) {
			this._registerDecorationType(key);
		}

		const decorationRule = this._decorationRules.get(key);
		if (!decorationRule) {
			return;
		}

		const existingDecorations = this._decortionKeyToIds.get(key) || [];
		const newDecorations = this.viewModel.getCellsInRange(range).map(cell => ({
			handle: cell.handle,
			options: { className: decorationRule.className, outputClassName: decorationRule.className, topClassName: decorationRule.topClassName }
		}));

		this._decortionKeyToIds.set(key, this.deltaCellDecorations(existingDecorations, newDecorations));
	}