src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts/NotebookCellList/elementAt
class NotebookCellList:	elementAt(position: number): ICellViewModel | undefined {
		if (!this.view.length) {
			return undefined;
		}

		const idx = this.view.indexAt(position);
		const clamped = clamp(idx, 0, this.view.length - 1);
		return this.element(clamped);
	}