function IncludesObservable(source, elem, idx) {
      var n = +idx || 0;
      Math.abs(n) === Infinity && (n = 0);

      this.source = source;
      this._elem = elem;
      this._n = n;
      __super__.call(this);
    }
Determines whether all elements of an observable sequence satisfy a condition.
@param {Function} [predicate] A function to test each element for a condition.
@param {Any} [thisArg] Object to use as this when executing callback.
@returns {Observable} An observable sequence containing a single element determining whether all elements in the source sequence pass the test in the specified predicate.