function Defer(factory) {
      this._f = factory;
      __super__.call(this);
    }
Creates an observable sequence from a specified subscribe method implementation.
@example
 var res = Rx.Observable.create(function (observer) { return function () { } );
 var res = Rx.Observable.create(function (observer) { return Rx.Disposable.empty; } );
 var res = Rx.Observable.create(function (observer) { } );
@param {Function} subscribe Implementation of the resulting observable sequence's subscribe method, returning a function that will be wrapped in a Disposable.
@returns {Observable} The observable sequence with the specified implementation for the Subscribe method.