function ElementAtObservable(source, i, d) {
      this.source = source;
      this._i = i;
      this._d = d;
      __super__.call(this);
    }
Determines whether two sequences are equal by comparing the elements pairwise using a specified equality comparer.

@example
var res = res = source.sequenceEqual([1,2,3]);
var res = res = source.sequenceEqual([{ value: 42 }], function (x, y) { return x.value === y.value; });
3 - res = source.sequenceEqual(Rx.Observable.returnValue(42));
4 - res = source.sequenceEqual(Rx.Observable.returnValue({ value: 42 }), function (x, y) { return x.value === y.value; });
@param {Observable} second Second observable sequence or array to compare.
@param {Function} [comparer] Comparer used to compare elements of both sequences.
@returns {Observable} An observable sequence that contains a single element which indicates whether both sequences are of equal length and their corresponding elements are equal according to the specified equality comparer.