src/vs/workbench/browser/parts/notifications/notificationsToasts.ts/NotificationsToasts/focusPrevious
class NotificationsToasts:	focusPrevious(): boolean {
		const toasts = this.getToasts(ToastVisibility.VISIBLE);
		for (let i = 0; i < toasts.length; i++) {
			const toast = toasts[i];
			if (toast.list.hasFocus()) {
				const previousToast = toasts[i - 1];
				if (previousToast) {
					previousToast.list.focusFirst();

					return true;
				}

				break;
			}
		}

		return false;
	}