src/vs/workbench/api/common/extHostNotebookKernels.ts/NotebookCellExecutionTask/updateOutputItems
class NotebookCellExecutionTask:	private async updateOutputItems(items: vscode.NotebookCellOutputItem | vscode.NotebookCellOutputItem[], output: vscode.NotebookCellOutput, append: boolean): Promise<void> {
		items = NotebookCellOutput.ensureUniqueMimeTypes(asArray(items), true);
		return this.updateSoon({
			editType: CellExecutionUpdateType.OutputItems,
			items: items.map(extHostTypeConverters.NotebookCellOutputItem.from),
			outputId: output.id,
			append
		});
	}