easy to unsubscribe...

subscription.extensions.ts

import { Subscription } from 'rxjs';

declare module 'rxjs/internal/Subscription' {
  interface Subscription {
    toUnsubscription(
      this: Subscription,
      sub: Subscription
    ): void;
  }
}
Subscription.prototype.toUnsubscription =
  function (
    this: Subscription,
    sub: Subscription
  ): void {
    sub.add(this);
  };

how to use it

import './subscription.extensions';
const sub = new Subscription();

const ob = interval(1000);
ob.subscribe(x => {
  console.log('show => ', x);
}).toUnsubscription(sub);

sub.unsubscribe();