src/vs/workbench/contrib/notebook/browser/controller/insertCellActions.ts/InsertCellCommand/runWithContext
class InsertCellCommand:	async runWithContext(accessor: ServicesAccessor, context: INotebookActionContext): Promise<void> {
		let newCell: CellViewModel | null = null;
		if (context.ui) {
			context.notebookEditor.focus();
		}

		const languageService = accessor.get(ILanguageService);
		if (context.cell) {
			const idx = context.notebookEditor.getCellIndex(context.cell);
			newCell = insertCell(languageService, context.notebookEditor, idx, this.kind, this.direction, undefined, true);
		} else {
			const focusRange = context.notebookEditor.getFocus();
			const next = Math.max(focusRange.end - 1, 0);
			newCell = insertCell(languageService, context.notebookEditor, next, this.kind, this.direction, undefined, true);
		}

		if (newCell) {
			context.notebookEditor.focusNotebookCell(newCell, this.focusEditor ? 'editor' : 'container');
		}
	}