import { Observable } from "rxjs/Observable";
import { Observer } from "rxjs/Observer";
import { Operator } from "rxjs/Operator";
import { Subscriber } from "rxjs/Subscriber";
import { Subscription, TeardownLogic } from "rxjs/Subscription";
import "rxjs/add/operator/map";

export class CustomObservable<T> extends Observable<T> {

    static create(value: number): CustomObservable<number> {

        return new CustomObservable((observer: Observer<number>) => {
            observer.next(value);
            observer.complete();
        });
    }

    constructor(subscribe?: <R>(subscriber: Subscriber<R>) => TeardownLogic) {
        super(subscribe);
    }
}

const ob = CustomObservable.create(1).map((value) => value + 1);

[add]: RxJS add import is missing: %s