message: refactor: correct the return of  after bad fix.
diff: @@ -7,5 +7,7 @@ import { isFunction } from './isFunction';
  * @param obj the object to test
  */
  export function isObservable<T>(obj: any): obj is Observable<T> {
  - return obj && (obj instanceof Observable || (isFunction(obj.lift) && isFunction(obj.subscribe)));
  + // The !! is to ensure that this publicly exposed function returns
  + // `false` if something like `null` or `0` is passed.
  + return !!obj && (obj instanceof Observable || (isFunction(obj.lift) && isFunction(obj.subscribe)));
  }
  