function IsEmptyObservable(source) {
      this.source = source;
      __super__.call(this);
    }
Determines whether any element of an observable sequence satisfies a condition if present, else if any items are in the sequence.
@param {Function} [predicate] A function to test each element for a condition.
@returns {Observable} An observable sequence containing a single element determining whether any elements in the source sequence pass the test in the specified predicate if given, else if any items are in the sequence.