src/vs/workbench/contrib/terminal/browser/terminalService.ts/TerminalService/_showTerminalCloseConfirmation
class TerminalService:	protected async _showTerminalCloseConfirmation(singleTerminal?: boolean): Promise<boolean> {
		let message: string;
		if (this.instances.length === 1 || singleTerminal) {
			message = nls.localize('terminalService.terminalCloseConfirmationSingular', "There is an active terminal session, do you want to kill it?");
		} else {
			message = nls.localize('terminalService.terminalCloseConfirmationPlural', "There are {0} active terminal sessions, do you want to kill them?", this.instances.length);
		}
		const res = await this._dialogService.confirm({
			message,
			type: 'warning',
		});
		return !res.confirmed;
	}