///
module Rx {
export interface Observable {
/**
* Determines whether an observable sequence includes a specified element with an optional equality comparer.
* @param searchElement The value to locate in the source sequence.
* @param {Number} [fromIndex] An equality comparer to compare elements.
* @returns {Observable} An observable sequence containing a single element determining whether the source sequence includes an element that has the specified value from the given index.
*/
includes(value: T, comparer?: _Comparer): Observable;
}
}
(function () {
var o : Rx.Observable;
var b : Rx.Observable = o.includes('a');
});