Gal Falah's example for rxjs post

preventNull.ts

  notNullish<T>(input: null | undefined | T): boolean {
    return input !== null && input !== undefined;
  }

  registerToggleCall() {
    Interactor.onTogglingSomthing()
      .pipe(distinctUntilChanged(), filter(this.notNullish))
      .subscribe((_state: boolean) => {
        this.state = _state;
      });
  }