Arman Naeimi aRmanNM

# debian
sudo apt install linux-headers-amd64 build-essential

# fedora (might not be accurate!)
sudo dnf install kernel-devel<kernel_version>

	@Injectable({
	providedIn: 'root'
	})
	export class BookStoreService {
	private _books = new BehaviorSubject<Book[]>([]);
	public readonly books$: Observable<Book[]> = this._books.asObservable();

	constructor(private bookBackend: BookBackendService) {
	this.getBooks();
	}