src/vs/workbench/contrib/notebook/browser/contrib/coreActions.ts/InsertCellCommand/runWithContext
class InsertCellCommand:	async runWithContext(accessor: ServicesAccessor, context: INotebookActionContext): Promise<void> {
		let newCell: CellViewModel | null = null;
		if (context.cell) {
			newCell = context.notebookEditor.insertNotebookCell(context.cell, this.kind, this.direction, undefined, true);
		} else {
			const focusRange = context.notebookEditor.getFocus();
			const next = focusRange.end - 1;
			newCell = context.notebookEditor.insertNotebookCell(context.notebookEditor.viewModel.viewCells[next], this.kind, this.direction, undefined, true);
		}

		if (newCell) {
			context.notebookEditor.focusNotebookCell(newCell, 'editor');
		}
	}