src/vs/workbench/contrib/notebook/browser/viewModel/notebookViewModel.ts/NotebookViewModel/cellAt
class NotebookViewModel:	cellAt(index: number): CellViewModel | undefined {
		// if (index < 0 || index >= this.length) {
		// 	throw new Error(`Invalid index ${index}`);
		// }

		return this._viewCells[index];
	}