public IObservable <Unit> Login(string userName, string password)
{
var loginRequestModel = new LoginRequestModel(userName, password);
return(_usersApi.Login(loginRequestModel)
.ObserveOn(RxApp.TaskpoolScheduler)
.Select(m => m.Token)
.Do(t => _settingService.Token = t)
.Select(u => Unit.Default));
}