class SomeClass {
propA: any;
propB: any;

@Subjectize('propA')
propA$ = new ReplaySubject(1);

@SubjectizeProps(['propA', 'propB'])
propAB$ = new ReplaySubject(1);
}

const instance = new SomeClass();
instance.propA = 'A';
instance.propB = 'B';

// would print 'A'
instance.propA$.subscribe(console.log);

// would print ['propA', 'A'], then ['propB', 'B']
instance.propAB$.subscribe(console.log);

@Component({
selector: "app-counter",
templateUrl: "./counter.component.html",
styleUrls: []
})
export class CounterComponent {
@Input()
count: number;